Many pre op patients already own crutches and are experts at using them. If that statement applies to you, consider yourself lucky. If you are new to crutches, visit your local medical supply house and try out different models. The standard wooden crutch, that goes under your arm, is familiar to most of us. A better option might be metal, forearm crutches. They are lighter, smaller in size, and once you adapt to them, more maneuverable. They are generally not very expensive. High quality rubber crutch tips, which have a larger surface area, and a smoother ride can be purchased through the internet.
You may want to consider looking at Bent Knee Walkers as an option. Many amputees like the additional freedom it gives your arms, especially around the house.