Some of the bigger US tax preparation companies have expat tax experts. H&R does. I didn't use them but I know someone who did and was happy.
There is some good expat tax info on these forums if you look, including from a couple of people that posted in this thread.
*************** isn't a bad place to start as well. The vast majority of Americans that I worked with overseas got audited, many twice, including me. It is best to plan ahead, which of course I didn't do. Luckily I got it right. Just lucky.