Unreal Tournament 2004

Unreal Tournament is very much an old-style FPS game. It follows more the style of Quake and the earlier Doom multiplayer than Counterstrike or Medal of Honor. Thus, fighting effectively in Unreal Tournament is very different from fighting effectively in Counterstrike.

Basics
There are several things that the newbie should keep in mind:


 * Don't be a statue. When standing around, especially in open territory, it's easy to hit you. More so when you're getting involved in a brawl. Keep moving and it'll be harder to hit you.
 * Weapons have secondaries. Experiment if you can, if you aren't familiar with the weapons. Flak cannons can shoot flak shells over medium distances aside from the normal shrapnel burst. Rocket Launchers can load up to three rockets at a go and launch them in a spiral pattern towards an enemy. See what you can find.
 * Familiarize yourself with a weapon. It's not necessary to be a master of all the weapons. All that's necessary to be good at this game is being very good at one or two weapons and being able to use all the others to defend yourself while you run for your weapon of expertise.
 * Campers are easier to locate. If you aren't using a lightning gun where the lightning bolt instantly gives you away, the puff of smoke from your sniper rifle will definitely make you easier to find. Staying in one place too long is like hanging a nice inviting "FRAG ME" sign around your neck, especially when you've just pissed someone off by killing them or their teammates.
 * Shooting at someone's corpse after you've killed them is usually taken as an insult and brings up the competition to a much more personal level. Unless you're something of an asshole, don't do it.

More Advanced Things

 * Dodging. Tapping in one direction twice quickly executes a quick dodge. Master this and it'll save your life many times over. You can use it when, say, you see a rocket rushing straight at your face, or when you suddenly notice the big smiley face on the flak shell growing larger...
 * Support. In team-based games not everyone can go out into the field and run around fragging the other team. Someone has to stay behind and keep the base (or the flag) safe. And since the entire enemy team generally would like nothing better than to get into the base and steal your flag, you probably want more than one person. Just in case.
 * Pick your targets. If you see the enemy ball/flag carrier in front of you, and a bunch of enemy goons about to block your way, don't bother with the goons that much. Your priority is the enemy ball/flag carrier. If you can take care of the enemy goons quickly, feel free; but remember the flag carrier is still your higher priority.

L337ness

 * Practice. Become one with your weapons. Learn to flow within combat, picking off goons and targets effortlessly. Learn how to instinctively target an opponent with your weapon of choice so that regardless of his range or speed you can still hit. All of this will only come with practice. There is no shortcut to 1337ness.