Matching your footwear selection to your pack weight, foot shape, walking style.
Selecting the proper footwear for a long distance backpacking trip will significantly reduce blisters, foot pain, corns, and plantar facistis.
The first task is to identify the type of walker you are, the second is to provide impact cushioning and foot support that suits your walking style, and the third task is to properly select the footwear that suits your foot shape and provides the support necessary for the load you will be carrying and the terrain you will be carrying it across.
Finally, you must fit your new footwear so that the correct support and cushioning inserts perfectly compliment the boot size to fit your foot.
If you complete these tasks successfully, then properly break-in the boots before hitting the trail, you have a pretty good chance of crossing miles of difficult terrain with a heavy load without foot problems.
The goal is to set up yourself up with the proper footwear that suits your backpacking load, compliments your walking style, and will properly protect your feet from the stresses brought on by the difficult terrain and weather conditions encountered in the High Sierras.
The above video describes the basics of the boot selection process, and the Hiking Boot Section Guide on the trail guide discusses boot construction.