The general rules of flying long haul are to sleep going east and stay awake going west. If I plan on sleeping on the plane going east, I like to leave as late as possible in the day from my departure city - e.g., 7:00PM + in LA for Europe.
For flights going west I like to leave really late - 11:00PM + (again assuming LA) if I plan on sleeping. My second choice would be to leave early in the day and catch a couple of hours of sleep early in the flight and then get up.
As has been stated, drink plenty of water and avoid alcohol. I don't like pills for a variety of reasons the least of which is that if the flight is diverted for some reason you don't want to get dragged of the plane in your sleep.
For your specific situation, I would catch first flight out of ATL and sleep for an hour or so at the begining of the flight. Think about eye shades, ear plugs and a neck pillow if you want to sleep. These can help make it much easier to get some sleep.
Other tricks are to set your watch to the time zone of your destination city as soon as you get on the plane and don't think about the time "back home". Resist the temptation to take a nap when you get to HI and go to bed at your normal time (HI time). Getting fresh air and getting some exercise can help you make it through what is a long day.
If you can make it through the first day and sleep in to a reasonable hour the next morining you'll be in good shape!
Good luck and have a great flight!