To add to the good advice so far: Know your aircraft. Is its short-field performance limited by take-off or landing?
Most spam-cans can land in very short distances, but need more runway to take off from. This is generally a safe situation, since it's generally possible to take off in the specified distance (once all the safety factors have been added) regardless of your experience. In which case, all the advice from others on the thread is absolutely correct.
If you happen to be flying an aircraft which needs more runway for landing than it does for take-off, though, then lots of practice at a field with a bit of extra length is required first. You must be certain of being able to approach to exactly the point you want, at exactly the speed you need. Then measure the distance it takes you to stop on that runway (ideally in still wind, and at the same weight that you're planning on going to your short field), and add a safety factor to that to find your personal landing distances, which will improve as you practice.