I would use a 1 1/2 inch coil spring trap with offset jaws, either a bridger or sleepy creek. The most effective set for fox is a simple dirthole set. Get the book, The Dirthole Set and Its Variations by Charles Dobbins. It only cost about $9 and he goes through all of the tools, baits, trap preparation, and sets you need. It is an invaluable resourse for a beginner. I wouldn't boil and wax the traps like he does though. There is a product called speed dip that works great. You mix it with gasoline or lantern fuel and dip the traps in it and hang them in a tree until the petroleum odor is gone and they are ready to go, no waxing needed. If the traps are new run them through the dishwasher, if they are used scrub them with a wire brush and kerosene, then dip them.