Here are some tips specific to Deathmatch:

• Learn the map. When you know where every weapon is and where the Double Damage pickup is, you’ll have an easy time annihilating your enemies.
• Learn to use the acrobatic moves and when to use them. For example, don’t try to do a dodge over a pit, but double jump. Don’t double jump into a rocket; dodge it.
• Find wounded players, and eliminate them. For example, if you come to a fight between a group of players, kill the one who survives. He’ll be low on health and armor.
• Don’t spawn camp! If there is a Sniper Rifle or Lightning Gun available, don’t aim at a spot where players spawn. Not only is this a cheap way of getting kills, but chances are you could be kicked out of the server. It’s okay to find a position and snipe people as you see them, but not as soon as they come into the game.
• Don’t ever stop moving. Always run, jump, dodge, and do whatever to keep from standing still. A stationary target is an easy target.
• Grab everything in the map. If you have 99 health and come to a health pack, pick it up. Sure, you only get one point of health, but you could be stopping an enemy who really needs it from picking it up.
• With explosives, like the Rocket Launcher, aim at the feet of an enemy, or at a nearby wall. The splash damage will hurt and eventually kill the player, while a direct shot from a rocket very rarely hits.
• Circle-strafe as much as possible. To do this, walk around your opponent in a circular pattern, keeping your gun on the enemy. It makes you harder to hit, and the enemy will never leave your field of view.