There are lots of different opinions... But here's mine :]
Before you start pole work/any jumps, practise adjusting your horses gait/stride. See if you can push him forward into a longer trot/longer canter, and then bring him back again into a shorter stride. This is a skill you will definately need ater on when you start jumping courses/grids. The first thing I will do is lots of trot poles. Make sure they are at a good dustance for your horse, so he has to streth his stride just alittle. let him have a loose rein and find his way over the poles, and always keep him in the center. Make sure you keep your eyes up, and you can practise rising into your two point position over the poles, and absorbing the movement into your knees, and keeping your hands still. Once he is confident at trot poles, you can pick up your reinsa nd change the distances, asking him to shorten/lenghten the tro again. he will learn to watch where he puts his feet, and begin to judge distances. Once you can do all that quietly and confidently, you can raise the last pole in your series of trot poles up to a small crossrail. do all the excersizes you did as if it was just a pole. let him find his feet, and keep him centered and calm. Make sure you never jerk on his mouth, grab a hunk of mane if you need to keep your hands still. When he is confident with that, you can raise the crossrail a bit, or add in another one in front. When i'm teaching a horse to jump, I will always stick with gridwork for the first few months, ie. not just one jump, a few poles then a jump then another jump. Once you can trot a couple of small crossrails in a row, you can set up a crossrail with one pole in front about a strides distance. get him cantering balanced and calmy, then canter him through. the pole in front will make sure he takes of at the correct spot, making his first few jump from a canter easier until he learns to judge distance by himself. Once he can cnater a jumo comfortably, calmy and balance, you can set up another grid, this time just crossraisl and maybe a small vertical at the end. I like the pattern of 1-bounce-2-1 stride-3-2 strides-4, If you understand? Again it helps them learn distances and strides without having to rely on themselves so much. Throughout it all, make sure they stay in the center of the jumps and don't rush, lots of half halts. Once they can do this comfortable, you can start jumping related lines and small courses, and go from there!