What Trek-chick said. Take the brake caliper off too.

You may have to take the fork (once its off the bike) to the shop if you need to remove the crown race for the headset.

I've removed my shock as well before. I just removed the two bolts that anchor it to the frame and bagged everything. I ended up tying the front triangle and rear triangle of the bike together with a piece of rope, since the shock was no longer there to hold them together. I have no idea if this is necessary or not, but it gave me some peace of mind. You might want to check the owner's manual for the frame and see if there are any special cautions or instructions.