Torsion springs are the kind wound-up on a rod above the garage door opening. When one breaks the other often follows, so save the cost of another service call, and have both replaced when one breaks. Many people have been maimed or killed tightening or releasing these springs. Hire a professional. They look something like long handled bolt cutters but, the business end it a ratchet to hold the bar as you tension the spring.
Skydiving is much safer.
Clopay recently came out with a torsion spring that uses an electric drill to tension it. If you have this new concept spring on your door, it's probably safe enough to do yourself. But, if you don't have this kind of spring now, you will have to remove the tension on your old style one that's not broken and that's dangerous. However, some safety measures are in order. I keep looking for a how-to description to put here but haven't found one.