What you do to your tree in its first few years of life will affect its shape, strength, and even its life span. In importance, early purning must rank just after selecting the right tree for the site, and careful planting.
Caution: Do not prune too high too quickly. To "lift" (raise) the crown, remove lower limbs over several years. No more than 1/3 of the live crown should ever be removed in a single cutting.
Attached is a diagram of pruning for form.