While most people associate death metal music with a bunch of guys grunting and slapping detuned guitars randomly, there's a multitude of reasons why this genre maintains a strong following and earns the fierce loyalty of many listeners worldwide. If you're curious about death metal, here's you're chance to learn, appreciate, listen, and enjoy.

[edit] Steps

Learn about the history and characteristics of death metal. It's probably more interesting and complex than you thought -- many of the stereotypes of death metal music and its artists aren't true at all. They are not all lazy, animal-sacrificing psychos; most are actually normal people with family, friends, and complex off-stage personalities.
Listen beyond the crunching guitars and harsh singing. Although the rough guitar sound and grating vocals that permeate all of death metal can take a little getting used to (especially if your ears are accustomed to softer sounds), it's more than just noise. There are melodies, patterns, and complexities to be appreciated if you listen attentively enough.
If you really don’t understand the harsh death grunts, don’t be afraid to look at them on a lyrics website. Two great lyrics websites are metal-archives.com and darklyrics.com. You might be surprised by the complexity and large vocabulary found in the lyrics. A common misconception of heavy metal music is that the lyrics are very vulgar, using a lot of bad language. However, heavy metal music in general is surprisingly lacking in the "F___ it all! F___ this world! F___ everything that you stand for" type lyrics seen in bands like Slipknot. To quickly get into the death metal scene, then start with Arch Enemy. Some of their songs may help get into the tone and the general death metal scene, without starting too hardcore.
Realize that playing and singing death metal requires enormous practice and skill. Even bass players, who don't do the complex leads and melodies associated with death metal guitar, may practice one piece of music for as long as a full year just for an audition.
Behemoth

Watch a live death metal performance. Observe how the group members manipulate the instruments. Especially if you've ever tried to play those instruments yourself, you'll probably be amazed with how skillfully they play. It takes practice, and dedication, which challenges the stereotype of metal heads being lazy and careless. You might also be surprised about how energetic some of the performers are.
Remember that in death metal, unlike many other genres, each band almost always writes their own music. That includes the riffs, drums, solos, and lyrics. Writing their own music demonstrates another dimension of talent, as does making the music sound more personal and less manufactured.
Understand the context and subject matter. Death metal (mostly brutal and old-school) lyrics and themes, while not always to be taken completely seriously, celebrate the outer extremes of human experience, such as the motivations of serial killers, gore, isolation, and death itself. Death metal is less about generic anger and more about empathy for people who suffer from despair, isolation, and an acute sense of unfair ostracism from society. Also, many bands (mostly progressive and melodic) will cover other topics not usually associated with death, such as mythology, philosophy, personal relations, religion, society, sience and even love. Very few Death Metal bands have Satanic/Anti-Christian lyrics, but they get much of the media attention. (If you are seriously against Satanic lyrics, Deicide and Immolation are both bands you may wish avoid.)
Learn about the sub-genres. Not all death metal is the same. The genre contains many sub-genres that can frequently mix and intermingle with each other. As a result, it may be difficult to ascribe a band under a single sub-genre. Here's a general guideline to get you started:
- Blackened: Akercocke, Behemoth, Belphegor, Dissection, God Dethroned, Sacramentum, Zyklon
- Brutal: Aborted, Blood Red Throne, Cannibal Corpse, Deeds of Flesh, Deicide, Deranged, Disavowed, Disgorge, Hate Eternal, Immolation, Krisiun, Nile, Skinless and Wormed
- Old School: Autopsy, Death, Dismember, Entombed, Morbid Angel, Obituary, Possessed, Benediction, Pestilence.
- Goregrind: Carcass, Terminally Your Aborted Ghost, Anal Bleeding, Guttural Engorgement, XXX Maniak
- Grindcore: Anal Cunt, Circle of Dead Children, Dying Fetus, Phobia, Napalm Death, Rotten Sound, Terrorizer
- Death/Grind: Cattle Decapitation, Cauterized, Dead Infection
- Melodic: Children of Bodom, Arch Enemy, At Odds with God, At the Gates, Dark Tranquility, Dethklok, Norther, Hypocrisy, Sacrilege, Soilwork, Wintersun, Disarmonia Mundi, Heaven Shall Burn, Amon Amarth, In Flames
- Progressive: Akercocke, Anata, Atheist, Becoming the Archetype, Cynic, Death, Edge of Sanity, Nocturnus, Opeth, Quo Vadis, Sadist, The Faceless
- Slam: Devourment, Dying Fetus, Internal Bleeding, Soils of Fate
- Technical: Beneath The Massacre, Cryptopsy, Cynic, Death, Decapitated, Gorguts, Immolation, Necrophagist, Nile, Ominous, Origin, Pestilence, Spawn of Possession, Suffocation, Visceral Bleeding, Psycroptic
- Death Metal/Thrash Metal: Abysmal Dawn, Possessed, Malevolent Creation, Vader, Slayer
Respect the artists. The greatest death metallers almost can't make a living with what they do, and yet the musicians in these bands continue on in spite of their obscurity. Death metal is so non-mainstream that its musicians have to work incredibly hard for their career sales to reach even a million copies (which less than 6 death metal musicians have actually done.)

[edit] Tips

Keep in mind that all genres and sub-genres are under heated debate, so do not adhere to a single definition too seriously.
Many great death metal bands never had a big record company behind them to support and promote their music. They are hidden treasures. Look around and discover what MTV ignored.
Some Death Metal bands guitarists are the most talented guitarists in the world. Their solos are so complex, that their standards reach to some of the best legendary guitarists.
For an example of this, listen, or watch a video of Necrophagist's "Fermented Offal Discharge", I would compare the solo in that to some of Van Halen's work.
Death metal lyrics elaborate on the details of extreme acts, including mutilation, dissection, rape and necrophilia. Sociologist Keith Kahn-Harris (author of Extreme Metal: Music and Culture on the Edge) commented that this may be attributed to a "fascination" with the human body that all people share to some degree, a "primal desire", and that although the genre often glamorizes violence and obscurities, there is as much fear and disgust amid the exploration.
One way to appreciate death metal is to think of it as an extreme form of over-the-top entertainment, like horror movies.

[edit] Warnings

There are many negative generalizations surrounding death metal. If you become enamored with death metal, be prepared for raised eyebrows and grimaces -- ignore them. Using this article may help your cause, if you choose to address them.
Death Metal is a typically anti-religious genre of music. However, Death Metal also covers many subjects and trains of thought. Death Metal is a very multi-branched entity. There are even Christians in Death Metal; you just have to look for them harder. Another idea would be to avoid listening to music that is fundamentally anti-christian and anti-religious in nature.