Wow, great thread.
I'm a DM player, never really cared for CTF, so I guess strategies vary there. From a pure "killing the other guy" standpoint, I've improved greatly over the last few weeks (just started playing about three months ago since I got DSL).
It seems to progress from "knowing the maps" to "knowing the weapons" to "knowing the best routes of movement" to "knowing your opponent". Once you know all four, it becomes mental, which is my biggest hindrance at this point.
I doubt it was planned this way, but UT works out alot like Golf. If anyone here plays they know what I mean. It requires total concentration, at all times. If you slack off for an instant against a better player, you're dead.
I find that the first couple of games I play every day are average, with me ending up middle of the pack in a team game, then after four or five games, I start to end up at or near the top each match, then from that point my last few games end up with me having as many kills as everyone else in the game combined. I suppose some of that is taking a few matches to nail the techniques of your opponent, some of it just "getting in a groove".
One thing I've done to improve the end result quite a bit, is study the maps intensively. For each map, there's a route of movement and technique that's overly common. Once you've figured out what those tendencies are for other players, take an alternate route to surprise them. If I get first look at another player, he better be damn good to get me in that little skirmish that ensues. If I'm taking odd routes throughout the map, chances are I'll stumble across you before you stumble across me, therefore I have the advantage. Against equal players I'll win by a few, against lesser players I'll own. Against better players I can hang with them, and hopefully luck into a win here and there with this method.
I guess my rules of thumb are never get caught without three weapon options to choose from, never get snuck up on while standing still, and if you ride a lift or round a corner once, don't DARE ride or round it again within 10 seconds time.
BTW, I use number pad for navigation, arrowed keys as movement, 7/1 and 9/3 strafe, with plus key as jump and insert/home/page/end/del buttons as weapon binds. Mouse buttons for fire/alternate fire.
Xayd