been playing tribes 2 for about 5 years now and here are some basic rules that I noticed help my game, most veterans here wont be surprised by anything on this list but it might help a noob or two.
1) play fair, have fun - yes I know you like to win, I do to, but cheating will only help get banned\kicked, and besides there isn't a lot of things more embarrassing then using an aimbot and still getting your ass kicked so don't do it.
2) knowledge is power - they say knowing is half the battle, the saying is especially true in tribes.
first thing I do when the game starts is to open the map and look where are the turrets, base, v-pad, sensors, and of course flag and memorise this places (after a few time playing the same map you don't even need to do that), that way i know the good routes to the enemy base and how best to avoid the turrets when low on health.
other then that good thing to memorise is just how much the enemy farmer like to deploy and whether they deploy more outside their base or inside so you know if it's best to use shear force or a stealthier approach to get inside.
3) help your team-mates - I always use beacons on the enemy builds, a good place to hide one is on the ceiling in the floor beneath the enemy turret\sensor so it doesn't get destroyed when it blows up.
another thing I'm amazed at is the lack of use of the laser-sight. if you see a tank trying to shoot at the enemy base poping out your laser-sight and aiming it at a valuable target for 2 seconds will give the tank gunner a good reference for all of his shoots, even after you stop aiming the laser.
also if your in a heavy and you see someone pointing it laser at something be nice and fire a few mortars at it.
4) know your strengths and weakness - know what roles your good at and what not so much, if you're having trouble with a speed movements perhaps it's best you'll stick to heavy defence, that's not to say you shouldn't switch to a role outside your comfort zone should the situation arise.
5) keep an eye on the ball, but don't hog it - in ctf always know where both flags are, remember that's the main goal and only do those things that will help your team getting the enemy flag while keeping yours, having the most kills is nice but it wont win you the game, give your shirke to the flag carrier, or lobing a disc towards the enemy flag carrier instead on that almost destroyed heavy you've been working on killing the last few minutes will do a lot more damage then killing an heavy that will respawn right away anyhow.
yet there is no need to go capping unless you know what your doing and it's best to give the flag to someone else when hurt then risking it, even if you wont get the points.
6) vehicles are a great tool, use them - everyone got a vehicle there good at so use it.
regarding the MPB I know it's not as fun as going on a bombing run yet it's an important asset to have so deploy it whenever you can.
7) only give orders if you are willing to take orders - don't bitch about the generator being down if the next time someone says the gen is down your going to ignore it and not fix it.