1. check to see if your AC compressor is engauging. If it isn't it's either 2 things, there is not 134a in the system because of a leak, or you have a bad relay. Before wasting your time checking relays, take a small screw driving and quickly push in/out on one of the high side or low side lines (just unscrew either the big or small cap on the ac lines. If a weak mist comes out, your system is probably empty due to a leak, if a quick burst comes out it's probably full and you have an electrical problem.
If there is no 134a check for the obvious, a hole in your condensor (infront of the radiator) all it takes is a small pebble at 100mph to put a hole in it. Look for oil spots and paint coming off on spots on your condensor, if you get a 134a sniffer it will be alot easier. If you can't find any leak you're going to have to get a certified shop to put die in the system.
If there is 134a start by checking all the fuses. If there good switching the AC compressor clutch relay with one just like it and see if the compressor turns on. If it doesn't, get the ETM and jump the relay, if it doesn't turn on, there is either a wiring problem after the relay, or in the Electrical part of the comrpessor clutch. If it does turn on, the problem is either the relay, or an electical problem before the relay (wiring, switch)
Hope this helps. Don't smoke when you're checking to see if there is 134a