One thing to remember when working on young horses, is getting them used to different footing. I never really did this too much, and we were on a trail (Thunder my 3 yr old gelding) and going down at a slant, he couldnt really get a good footing on the big round river rocks. To say the least, we slipped and he popped me off and I hit my back on a big rock. Another thing to remember that might get overlooked is toughening up the feet. After the first ride or so out on different terrain I noticed my gelding's frogs and what now were chewed up....not bad to where he was lame, but still roughened up a bit. Get them used to working on gravel and big rocks.