You cant go wrong with a fully enclosed pen of some type. If they are still getting in, hot wires on a timer for the night will keep most critters at bay. You can also run a trapping program, using live traps. If you are afraid that you will catch your own pets or the neighbors cat, and you have a large problem with raccoons, look up a product online called "the egg" for trapping raccoons, its even safe to use around kids because of the way it works.