So you want to ballroom dance? You're about to enter a world of class, tradition, and loads of fun. The good news is it's easier than you can imagine. The bad news is you'll still need to work. Ballroom dance is a somewhat artificial category including many styles of traditional partner dances from several parts of the world and different eras. The thing in common is the expectation that the dance is polite and the dancers' dance-floor relationship somewhat formal (Ballroom dancing is never "Dirty Dancing"--even the more sensual styles such as the Tango are stylized. The sexuality of the dance exists in innuendo, not in hot and sweaty contact between the dancers).

[edit] Steps

Learn that unlike most types of partner dancing, ballroom involves multiple styles. While you don't need to learn all of them you will need to learn a few core styles at first. Complicated dances such as the Bolero and paso doble can be picked up later, but if you want to go out dancing and not be stuck in a chair the whole night you'll need to know east coast swing, rumba cha-cha, tango, waltz, and fox trot.
Decide what you want to dance for. Do you want to do social dancing or do you want to compete? If it's the latter you'll need to supplement classes with private lessons. Do you want to go out each weekend or do you just need to look good at a wedding? A specific type of event might require that you learn only a few styles but you'll want to learn them in depth. You'll be better prepared for a night of casual social dancing if you learn basic steps for a number of dance styles(you will pick up more moves as you go out dancing, practice and the basics become familiar).
Find a teacher and a school you might try the phone directory or a quick Google search for "ballroom dance [name of your city]". Contact one or more of the schools and tell them what your goals for ballroom dancing. You want to find a good fit: Some schools, for example, specialize in competitive dancing, while others focus on helping first-time dancers gain the experience (and courage!) to brave the ballroom dance floor at their next wedding invitation. If you live near a college campus, take a look at their student clubs and activities. Many have ballroom dance teams that compete at a collegiate (rather than pro/am or professional) level, and many are open to non-student members.
Watch the prices as they will vary. You will want to be sure the school and your teacher are worth what you're paying. Group classes will generally be less expensive than private lessons, while the best specialized and personalized coaching for competitive ballroom dance can be a hundred times more expensive. The best ways to see if your dance lessons are worth it are to:
- Be sure you know what you want, and that your needs match your instructors' expertise and methods,
- Talk to the other students and see how long they've been at the studio (as a rule, experienced dancers won't stay long at overpriced dance classes) and
- Visit one or more dance classes. Many dance studios will offer potential students a free or low-cost initial lesson that will allow you to more easily find a good match between the studio and your goals.
Go to class. This may seem obvious but I'm constantly amazed at how often people skip class. It doesn't matter how good a teacher or dance studio, every time you miss a class, you won't benefit. If you find that a particular class time tends to run into scheduling conflicts, find another time in which you will be able to consistently attend.
Listen to ballroom music. Ask your teacher for a list of songs in the rhythm you're working on. Buy them as mp3s and listen to them in the background. You might also find some musical collections selected specifically for a particular dance.
Pick out the dance rhythm and count it aloud as the music plays. Many beginning dancers benefit from first clapping the beat with the music. Yet also as you listen, visualize the dancers moving to the music. Feel the style of the dance, in addition to its rhythm.
Practice. Most studios have practice sessions outside of lessons. Go. Don't be afraid to ask more experienced dancers for help.
Dance! You're in this to learn how to dance so go dancing. Even after your first lesson you can "dance" in your mind as you listen to the music or even to try some steps in a safe corner. If you learn two moves a lesson then by your third lesson you know six moves. That's enough to go dancing and look like you truly belong on the dance floor.

[edit] Tips

Music and dance go hand-in-hand. Keep in mind that it is not only the time signature of the music (3/4, 4/4, etc.) but also the tempo and the style of the music that makes a great dance song. A great tango musical performance is every bit as spicy and edgy as are a great tango dance couple.
When you are learning a new dance step, remember that great riffs and striking solos are not nearly as important in dancing as is a steady and obvious beat. There will be plenty of time to experiment with the alternative sounds once you are comfortable with the dance step.
Ask everyone to dance! Beginners and experienced dancers will both help you to improve your dancing. Beginners make you check what you know. Experienced dancers will correct you. As a rule ballroom dancers don't say no when you ask them to dance. And remember: ballroom etiquette precludes dancing more than two dances in a row with the same person. If you only want to dance with your boyfriend/girlfriend you can stay home.
Say yes! If someone asks you to dance say yes! It is good etiquette to say yes, and rude to say no. Ballroom dancing is not in itself "dating" and neither partner should attempt to use the physical closeness of ballroom dancing to imply anything else.
It is especially crude and unchivalrous to exploit the physical closeness of ballroom dancing in any way that would cause your partner discomfort. Even when the dance partners are a long term loving couple, ballroom dance requires a certain savoir faire, a style that is based on dancers both utilizing good posture, maintaining careful balance, and attending to the music and to the other dancers on the floor.
When facing a new partner in one of the basic positions, each dancer should look slightly away from the other's face, usually over their shoulder. Otherwise, the intensity of staring into the eyes of someone so physically close can be uncomfortable, even a bit frightening.
It is a fact of life that people come in all shapes and sizes. Adjust your position and your dancing style to accommodate your partner, especially if height differences or body size might otherwise cause uncomfortable body contact. Remember that ballroom dancing is about grace, polish and courtesy.
POSTURE
In ballroom dancing, posture is critical. While style is explicitly judged in competition dancing, it is no less important in social ballroom dancing. Good dance posture isn't just about looks, it affects how well a couple will move together.
A big part of the magic of ballroom dancing is the wonder of how two people can move so effortlessly across the floor, as if they were one. This isn't an optical illusion, but it doesn't automatically happen, either. The secret to dancing together, as opposed to dancing near one another, is communication.
This communication is not verbal, except when first learning a dance step. Instead it is physical. In most ballroom dances coordination messages are communicated through the parts of the dancers' bodies that are in contact: Often the lead's left and the partner's right hands, the lead's right hand at about the mid point of the partner's back, the partner's left hand on the lead's right shoulder, so that the lead's right elbow and partner's left elbow touch.
This communication isn't conveyed through some special code, but is rather accomplished through the subtle body movements that can easily be detected when both dancers are standing upright, with good posture. When the lead moves forward, for example, the right shoulder, left hand, right hand and foot will all move simultaneously. Thus the partner feels the movement in the left hand (on the lead's right shoulder), the right hand (resting in the lead's left hand) and on the back (the lead's right hand moving "backwards" as the step begins). Likewise, as long as both dancers maintain good posture, and the lead moves decisively and consistently (keeping body parallel to the partner, moving the whole upright body (instead of either leaning in or away) the partner can easily detect movement to the right, left, or forward.
In order for this communication to work, the postures of both dancers must be maintained, and any movement of the lead must be "signaled" by the concerted movement of the entire body. Likewise the points of contact--where the messages are communicated from each dancer to the other--must be maintained so that any message received will be unambiguous.
If a lead is sloppy, and leans forward from the waist when not moving the entire body forward:
the partner will feel the right hand (in the lead's left hand),
the left hand (on the lead's right shoulder)
and the torso (as the lead's right hand moves away) all moving backward. In that both bodies should move together, these signals should indicate a backward step. Yet if the lead is simply leaning forward, instead of actually stepping forward, this will end with the dancers breaking their position, as the partner moves a step backward while the lead does not. The communication has failed.
If the lead maintains an erect posture, both hands, the right shoulder and the point of contact between right and left elbows will move only when a step is being indicated. Thus without saying a word, the lead can communicate "move forward (or left, right, or backwards) and the precise distance of the move, without saying a word.
Likewise the partner, if maintaining a good posture and constant communication points, will almost unconsciously sense the movement indicated. Each step learned from that position will be lead with some combination of those communication points, within a specific context. Experienced partners can move quickly and with great precision through a variety of complicated steps, without either dancer even consciously thinking about what will come next.
One frequent error, especially of long-legged men dancing with much shorter partners, is a stride that is just too large.
Ginger Rogers, the glamorous frequent partner of Fred Astaire has often been considered every bit the equal in dancing skill. "Because" the comparison goes, "she did every step that Fred Astaire did--backwards and in high heels!"
In most ballroom dances, the initial step is the lead's left foot moving forward and the partner's right foot stepping backwards. In that it is a usual thing to be able to step further forward than backward, the lead must be careful to keep the steps small. Besides, the illusion of floating across the dance floor is not created by a few large swooping strides, but rather by a quick succession of small, incremental steps. Keep the steps small and you will both look better and will maintain better balance in the bargain.

[edit] Warnings

Dance at the level of your partner. Don't try to do all your advanced new moves with someone who's just starting out. Social ballroom dancing should be enjoyable for everyone: Both dancers as well as anyone watching. There is no point in trying to make yourself look good by making your partner look bad. When a couple works together, dance is a thing of beauty.
Yes aerials (jumps and balancing moves) are cool. As a beginner you are not ready. Don't try them. Don't even ask about them until you've been dancing for at least a year. Dancing is physical and as with any physical activity if you do it wrong you can get hurt. Any dance step requiring one partner to rely on the other for balance should be approached only under the supervision of a dance instructor, and attempted only if both partners are familiar with their roles.
Ballroom dancing is at its heart, elegant. Think "elegant" as you practice. Dance is not a simple matter of learning where to move your feet, it is a new way of moving your entire body, in close coordination with someone else moving their entire body. You are far better off learning the basic steps so well you can almost float across the floor than by rushing into the complex steps and looking like a moose calf just learning how to walk. If you only know where to put your feet, you don't know the dance.