(Disclaimer: I am, at the time of this writing, a newbie in BZFlag matters. The info found here is mostly from the forums at http://my.BZFlag.org/bb/, mixed with the little experience I have)
One of the most important objectives in BZFlag is to stay alive (if not the most important!) "Staying alive" means "not getting your tank blown up", because when it's blown up, you can't have fun driving around shooting the enemy tanks, which is why you play BZFlag in the first place, right? On the positive side, you're only "dead" for about 3 seconds, and after that you can get back into the mayhem. There are 3 ways to die in BZFlag:
* You get shot * Your team flag gets captured by an opposing team in a Capture The Flag (CTF) match * You self destruct
So, staying alive basically boils down to awoiding these 2 situations; getting shot, and getting your team flag captured by the enemy - avoiding to self destruct is easy; just don't hit the DEL ("delete") button.
Avoid getting shot
An obvious way to avoid getting shot, is to stay away from tanks that might fire shots at you. However, this is not very desirable (if you are out of their firing range, they are out of yours, and thus you can't blow up other tanks which is the fun part!). And it's not possible to hide forever, so you will eventually have to deal with situations where bullets are coming in your direction...
It's possible for you to blow up your own tank by shooting yourself. This can be done in matches where bullets can ricochet, which means that a bullet hits something, like a wall or a building for instance, and then springs off in a new direction. So if you fire directly at a wall in a game where the ricochet option is "on", the bullet will spring back and possibly hit your own tank, thus blowing it up! If you shoot yourself (by accident or otherwise) you see a message saying "shot myself", your bodycount will go up, and everyone else in the match gets to laugh at you.
You can avoid this by giving your shooting a little thought, ie don't stand close to hard objects (like buildings and walls) while firing directly at them, or fire at them in sharp angles, sending your bullets away from you even after the ricochet.
Not only can you shoot yourself, your teammates, your brothers in arms, can shoot you too!
Dodging means getting your tank out of a bullets path. If you watch the movie "The Matrix", you'll get a fairly good idea of what dodging is all about.
Jumping in order to avoid enemy fire is generally considered a bad idea.
Prevent the enemy from capturing your teams flag
A note on self destruction
Some people self destruct in order to avoid getting shot. This may sound a bit strange at first, but the idea is that if you self destruct and thus avoid getting shot, you prevent your enemy from getting a hit point as a result of shooting you - and keeping your enemys hit count down is desirable.
Please don't do this!
It is generally frowned upon - if your enemy has you cornered, and your destruction is the only possible result in this situation, then of course he deserves the point. So please, either fight your way out, or die with honour!