Grab a handrail, if one is available, and hold both crutches under your other arm. If there is no handrail, use both crutches as you would normally. Ask someone for assistance, if possible.
Stand at the edge of the step, with the crutches near the middle.
Lower your crutches to the next step and step down with your weak leg, using the crutches to support the majority of your weight. If you are unable to place any weight on your leg, you may need to ask someone to help you get down the stairs without hurting yourself.
Bring your strong foot down and repeat the procedure until you get to the bottom of the steps.
Hop down the steps on your good foot, if you are unable to place any weight at all on your bad leg. Make sure you maintain hold on a handrail or wall to help maintain your balance. You may need to ask someone for help steady you on your way down. This friend can also hold your crutches for you if need be.