I thing I have built around 300 linear feet of stone retaining walls around the house over the past 20 years. I'm in the process of walling in the garden with a stone wall.
One retaining wall goes from 2 feet to almost 8 feet high and has been in place for 15 years. You have to have a good base nice and wide and the wall must lean into the bank if you don't want it to fall over.
I found that back filling the wall as you go up helps with placing the stones. A man down the road from me almost a mile did some dirt work around his house, more stone than dirt. He also is a logger and he used his log loader to build the stone wall, pretty slick.
The thing you have to watch out for the more is what is known as the granite kiss. I have had a few of those.
The granite kiss is also the title of a book on stonewall building. Just finished that one. Also Knucklehead's recommendtaion. The granite kiss was a bit more detailed, but also a bit more "artsy". I'd recommend reading both. Good pictures and illustrations on what to do & what not to do.