The biggest problem with getting players into the clan scene, I think, is the skill gap. You can't really expect new players to match up against people that have been playing for 10 years and stand a chance. Regardless of how good a game is, if you're going against players that are just going to completely dominate you, it isn't fun. I'm not really sure what to do about that.
They wont stand a chance, but can they expect to? Isn't every game the same? You're not going to start a game and beat top teams, there's a huge skill gap. But there is a noticeable difference between DP and other games, (there are weak teams that could be beaten by new players in any game) - but, new players to DP come in completely blind, they don't know what to expect. Youtube videos are usually awful quality, and super fast with some random fluke shot etc... Forums aren't really useful, #paintball isn't very useful.
Tutorial map / videos will help this, because new players will at least get a basic idea on the jumping, instead of going: "HOW DO YOU FLY?!?!" - they will comprehend how the game works and know how to work on it.
A main-page gameplay/introduction video to the game would help too. It also let's new players know what to expect. (Maybe even a library of these videos, with different sections that can show different common maps etc..). Don't know, just things that remove them coming into the game blind.
HR4 Textures ON DOWNLOAD! This not only keeps players around because of the look, but also reduces the advantage of new players to older players. You can see models MUCH easier with good quality textures.
Something with IRC or built in friendlist type thing - let's new players have a way of communicating with each other - let's them integrate with competitive players (If IRC) and also let's them get instant responses to their questions. But right now, nobody pays attention to #paintball, because nobody uses it other than toxiic's 100 multiple accounts.
UPDATE THE WEBSITE! Make the FAQ's easier to find. Add FAQ's like: How do I reduce lag? (and many other things). Give them a easier to find resource, because if they post something on forums that has been asked before, they will get flamed, not helped, for not using 'search'. Let them find common questions. Also, using search finds more flaming threads than useful ones.
You can't remove the skill difference between new and old players, but you can certainly make it less of a problem. There's a lot of things that can be done to improve the game, and that will take a long time to do, but I think the way to integrate new players into the competitive scene starts with letting them know what the game is about, before they start the game.