Might be able to get you on the fast track if you can give us some symptoms. Does it just not try to start at all, or does it cough and sputter a bit? Got a good charge on the battery?
Fuel, Spark, and Compression. If the motor has these three things, it HAS to run wether it likes it or not.
Check that fuel is getting through the tank, petcock, and through the carbs. Easy way would be to take the spark plugs out and smell them. If one doesn't smell like gas, work your way through the fuel delivery system.
Take each spark plug out, put it back in it's cap, and ground it on the motor. Try to start it and look for a spark. All four should be giving you a spark. Helps to have someone lend a hand here. Do one at a time.
Got a compression tester?
After you get it running you can address all the maintenance items. Even with these out of adjustment or just in a bad way, the motor will still run to a degree.
This is a good website for a newb:
http://www.dansmc.com/