Can I prevent bed bugs?
Two words: diatomaceous earth. This stuff is sold at pool and gardening stores, and it's that killer combination of inert to you but lethal to insects. It's basically microscopically razor-sharp stone, and physical contact with it tends to kill insects by shredding their carapaces and drying them out from the inside (ew). You could surround your bed's legs with this stuff. Put in your mattress, too.

For much, much more info, you may be interested in this account of how one enterprising homeowner managed to not only prevent bedbugs but also treat an existing infestation: http://softsolder.com/2010/11/08/bed-bugs-overview/