The best method i've heard of, minus a quiet tipple, is to relax your body starting from the toes upwards. It's muscular relaxation of hold/stress the muscle then relax. Then onto the next one.
It seems to work okay - but sometimes you just gotta accept yr gonna get stuff all sleep and deal with it. I have a night once every couple of months where I just cannot sleep and get like two hours worth.
Which sh*ts me as I hate being tired, i'd rather be hungover.