You should first do some work on trust. Get him used to you, spend time with him. Start getting him bombproof, show him new things - try a plastic bag on a stick or rustly things that he may be afraid of and slowly introduce them. make him see there is nothing to be afraid of - keep going until he is comfortable for you to rub a plastic bag all over his body or throw the leadrope over his legs, back, neck; everything. It will also make him much better when the time comes to break him in. Sinces hes still very young, riddend work wont be done for alteast another year, so get him used to everything until then. Get his groundwork good, and his halter leading. take him over poles and around cones inhand and get him used to your voice and the aids to walk on, stand e.t.c - keep it interesting. Once he has started to pick the voice commands up, set up a round pen, or try in a field with a cavesson and longe line, and begin to introduce longing - use the same commands and work his fitness up. You can then lunge him with a roller, or maybe a bridle too. if you have a nice light saddle, get him used to that too after the roller and get him used to the girth being done up, the stirrups and the feel of the bit in his mouth. If hes going well, you could then teach him turning aids with some long-reining. That should set you up nicely for ridden work later, or you can give him a rest to mature and then bring him back and all the preperation for breaking in should be pretty well strarted!