As Papakeith said, Welcome to the 500 club. (it takes a different breed:p )
*Skid plate & Bark busters for sure (as RM_guy said)
*I use 14/49 gearing-really spreads the power out, I ride mostly in the mountians,tight and tech.,but I clutch some also.
*Get a Brake Snake, the rear pedal arm is butter.
*Remove the chain cover over the countershaft sprocket, it clogs VERY badly with mud. But keep the case guard underneath.
*A set of lower,flatter,less pull-back Renthal Alum.bars helps the handling and takes out most of the vibration in your hands.
*With the correct jetting and ANY amount of throttle, you CAN't make it bog down and high gearing keeps the power smooth, so I don't run a flywheel weight.
*Correct sized springs are a must.
*Start adjusting with the rebound soft, they have too much from the factory for the woods.
*Nothing eats tires,chains,and sprockets like a CR500,you'll save money in the long run by buying top quality chains/sprocket.(I use PBI/RK O'ring)
*Forks have too much intial high speed damping,combined with too soft springs,means alot of shearing off of wet roots. A revalve is in your future,whether you go with Race Tech,just do it yourself,or have a shop do it.You probably won't be happy with the stock forks.
*Oh yeah,if you grab the rear fender to turn the bike around,you'll probably end up with a handfull of rear fender(been there,done that)
BTW,I'm in the western part of the state and been on CR500's since 1990,if you need anything else,hare scrambles schedules,bike questions, whatever, just ask.