Make sure it is a oil bath/dipper type, not an oil free. An oil free will burn up with constant use, plus they are alot louder than oil bath types. You want one that has a big cfm capability, that way it only needs to run for a short time for it to recover. Sometimes they have a recovery time from time of pressure drop to recovery. Make sure it is a model or maker you can get part's for in the future. Not some fly by night make. Take note of the cylinders if they have cooling fins, along with the lines and other parts on the outside, i.e. pressure switch is it adjustable? tank pressure gauge/line out pressure, warranty on the tank?, etc.. it's like buying a car that should last a lifetime. The two stage is really the best, unless you want to go with a three or four but for general use they are way overkill. On a two stage the larger cylinder feeds a high pressure to a smaller cylinder which then typically doubles the pressure on compression. Basically like a twin turbo setup. A great addition to a nice compressor is a great regulator/drier setup, don't go cheap here, just because you need a regulator that will control at high rates of flow, and not be a restriction. And spend a couple bucks on a automatic water drain for the tank.
Hope this helps.
