Ever get that feeling that you just want to kick someone when he or she gains a life or get the "You Win" screen? This is a simple guide of how to keep your pants on and not lose your cool.

[edit] Steps

Do not hit the controller on the ground or slam the keyboard. When you do this, the stuff inside of it will either break or disconnect and won't work again (e.g. character won't stop moving right because the joystick is messed up).
Hit something you know that it will not break (e.g. pillows, couch, etc.), but never hit the floor. You could damage something a lot more important than a controller.
Stop playing the game for 20 minutes; take a break, have a drink or watch some TV. You can always play another game, of course.
When you get back on the game, don't head right into the level. Warm up on the tutorial missions or the first level. When you are warmed up, you won't make as many careless mistakes (e.g. fall off an edge or walk into an explosive).
Get plenty of sleep, take care of your body, eat properly, and you'll be amazed at how well you play games due to sharp reaction times. Sleepiness, poor health, and dehydration lead to slower reaction time, which in turn lowers your skill in games that require fast thinking on your part.
Repeat steps as necessary.

[edit] Tips

Learn from your mistakes! Games are fun because they offer 'challenges'. So if you die (or fail a mission, or don't 'win' against a competitor), think, "That's OK, I'm only competing against myself, and I'm getting better all the time (if you are learning from your mistakes). If you don't know what you are doing wrong, check the instruction manual, go through the tutorial, or ask someone who knows the game better. We are all 'newbs' (new players) at first. Sometimes it's not you, but a game programmed stupidly, so just sigh and deal with it until you get past the 'dumb' parts.
Realize that not all battles can be won. Try to escape, and if you wish, come back after restoring your character's stats or at a higher level. Some battles are programmed so that they cannot be won in order to advance the story. Others are simply designed to be difficult. Some have a very particular weakness that may not be obvious at first. Pay attention to the scenario and do your best.
When you are dying, it is okay to stop for a while and strategize. After all, strategy is vital (charging in and button mashing is considered a strategy, but it usually is not the best one).
It doesn't matter if you win or lose!
Save often. The one thing you lose when you get a game over is any progress you made since you last saved. In some games, you won't always be able to save whenever you want, so take advantage of it while you can. At the earliest opportunity in the game when you can save, do it, otherwise you'll curse at the game due to having to start over (mainly on games with unskippable long intros).
Make a back up save, especially before entering a difficult area. Some times you can't leave an area until you complete it. If the area is too difficult, you could be trapped with no back up save. Having a back up save will allow you to get stronger, hone your skills, and make changes for a better strategy.
During boss fights, it's natural to focus on dealing as much damage as possible while trading blows. Change focus to avoiding being hit and attacking when it's safe in between the boss's attacks. This will draw the fight out longer but it can keep you alive long enough to outlast your opponent.
Some cheats may help ease your frustration and bypass a part of the game that you feel is too hard. However, cheats really defeat the purpose of a game, and should only be used if you've tried so many times (over a reasonable length of time) to get past a stage, that you're sure it is impossible.
All of the above can also work in real-life sports (except the cheating, try to remember to show a little sportsmanship).
Read the manual! Sometimes just re-reading the manual will remind you of a weapon or technique that you may have forgotten.
Try to remember that if you are playing multi-player, you could hurt one's feelings with a bad attitude.
Not all games follow one path. If you can't beat a difficult part in the main story, try completing any available side quests. You'll be rewarded with in-game stats or items, as well as the feeling of actually accomplishing something instead of a game over screen.
If the get a game over, it's not the end of the world. You'll be able to identify things that will prevent you from getting a game over next time, such as patterns that a boss follows, the locations of enemies throughout a level, or how to solve a puzzle.
If all else should fail, play on a lower difficulty setting. You'll get better knowledge of later bits of the level, and develop strategies to nail that sniper, 100% that solo, and find that powerful weapon.
If you lose, then just get away from the game, and think it out. Go to the bathroom and sit down use the restroom if you have to, this will give you time away from all the things that are bothering you, and let you think it over. Odds are you will be doing alot better at the game after clearing your head, this will also help in that you will not be as stressed from the game and notice your mistakes.
Try going to websites like GameFAQS for advice.
Some games are just impossible, yes they can be beaten, and alot of people might have beaten it, but not everyone is the same, sometimes people will come to a game they just can't beat. If that's the case then give up, or see if other people are having just as much trouble.

[edit] Warnings

Make sure that you're playing the right type of game. Some are poorly designed, not particularly fun and very frustrating to play. Check a gaming forum or go to a review website to avoid buying such games.
Using cheats might get you addicted to playing it the easy way. Use them as little as possible.
When playing online, whilst using Voice communication, do not "Rage" after you get killed. You'll just end up annoying and enraging your team mates which will aslo aggravate your own rage!
Do not go into an angry fit and lash out at others. Try to tell yourself that it is only a game!