http://www.nwf.org/backyard/This is a fun project ot do with kids and also a great way to attract beneficial critters to your veggie patch!
It is fairly easy. You pick a site, then plant native plants that supply food and shelter for your critters. Add a water source and you are done. For a few $$$ extra, you can order a certification sign to post by your garden.
We are doing ours in part shade under an oak tree. My kids decided that they want to attract toads, so we are adding an amphibian house (just an old board propped up on one side an surrounded by rocks and native ground cover plants). For a water source, I have an old trash can lid that I will partially bury and fill with gravel and water. Mosquito dunks should take car of the insect problem without hurting the beneficial critters. Either that or there is a battery powered device that "wiggles" the water periodically to discourage mosquitoes.
I bought a native deciduous holly that has berries in the winter for the food source, and will attempt to locate some native ground cover plants in the next week to finish the project off.
We are planting a toad garden (toads are great hunters of garden pests!), but you can do other types to attract hummingbirds, butterflies, whatever.