Here are my techniques, hopefully some will work well for you:
Fly overnight, think only in terms of local time at your destination in terms of eating and sleeping times.
Wear loose fiting clothes. Take your shoes off but wear socks and keep your jacket handy to use as a blanket if your cold or an extra pillow.
Ignore any movie offerings, eat a very light dinner, use the toilet then get comfortable.
I use a blow up pillow but I find it's more comfortable if not fully inflated (like a sleep number mattress, fill it to where it's most comfortable for you). Putting a sweater, t-shirt or something over the pillow makes it feel less plastic.
The eye shades are great on planes. I never use them elsewhere but got a free pair once on British Airways, tried them and now use them on long flights.
Pick some soothing music to listen to. If you don't have noise canceling headphones or your own tunes, use the planes headphones and put on some light classical or other calm music at a low volume.
I take one excedrin PM after dinner. Since I never take a sleep aid any other time, it seems to be plenty for me.
Regulate your breathing. Make sure you are taking full breaths. Breath in slowly until your lungs are full, hold for a second or two then breath out slowly and fully. You can regulate your heartbeat to help control anxiety or excitement by concentrating on breathing regularly.