Lighter is better. If you can't drag it out of a mudhole by yourself you may as well drive a car.

More suspension is better. The biggest advance with bikes is the suspension.

Keep it out of traffic and off of slippery surfaces. Seriously, look at the contact patch on a bike, ain't much.

I am resurrecting my dirtbike to see if I still have it in me. Some of the rubber? parts disintegrated while in storage.