When I started racing an old TT rider gave me some good advice - 'force yourself to go slow at first and concentrate on becoming smooth.' These days when I race I usually go nowhere near crashing, however when I started, I think I crashed at the first four meetings and once four times in one day. However I have probably got the wrong mentality. You get to know how to crash safely, and I've only ever had one really bad one where I copped an injury - a dislocated chromo- clavicular joint (worse than a broken collar bone, however it could have very easily killed me). Compare the risk with the likelihood and consequences of hitting a truck on a public road and getting run over by it. On a race track the other vehicles are all bikes going the same way with riders looking out for each other. Once you really know the circuit, everything should be hunky-dory, unless you are a panic merchant. I'd say one other thing - if you get on a race circuit and the power or braking characteristics of your bike give you anxiety, do some work on it before you do something nasty to yourself.