Keep your weight balanced by bending at the waist and elbows to shift some of your weight over the front wheel while you're seated. Your effort should be based on how long the hill appears to be. When climbing, it is wiser to choose too small a gear than too large. In a low gear, your feet will spin rapidly, but this uses less energy than pushing harder in a higher gear. In the proper gear, you can prepare for the tough part of the climb.
Concentration is important in two ways.
You must believe you are going to stay on your bike to the top of the hill and, depending on the terrain, you must look ahead for the proper line. This simply means that if there are rocks, ruts, curbs, or a combination of these, you must choose the easiest and most ridable line. Concentrate on what is directly ahead of you, yet glance beyond as well. Plan ahead and you will avoid coming to a sudden stop. When climbing a steep hill, you must balance your weight properly.