General idea is:
Turn bow of boat into the wind before rigging. When sail is in the boom and you are ready to hoist her up, make sure you leave a lot of slack on the main sheet. This allows the boom to move a bit and avoids craziness. Because you already parked your boat straight into the wind, the sail should be 'in irons' and won't do much to your boom.
Some people prefer to rig the boat/ hoist the main sail while she's already in the water. I don't.
Anybody else some comments? ...I am a windsurfer as well and relatively new to the sailing. Just bought a Hobie Getaway. Getting it in 3 weeks :-)