I use a microwave turntable that I picked up at Walmart for $2. Not real fancy, not real high-quality, but it has a nice flat area for parts and turns so I can get to all sides easily.
I usually secure parts with a loop of masking tape. Stick the tape down, stick the parts on top. You could also use a block of foam (all sorts of sizes and shapes available at places like Hobby Lobby, Michaels, etc.)