Please please please do not steam a suit!
Wool is a hair like the stuff on top of your head; when a suit has been finished, about an hour is spent pressing it, molding that hair into a shape, much like when a woman puts her hair in curlers. Pressing is an art form in itself which, when badly done, can destroy a suit. Likewise, steam in the hands of the inexperienced can ruin the careful shaping that the pressing has given it. Think of how women squeal about their hair when it is humid or rainy out; that's what steaming is going to do to your suit.
I hesitate to even suggest you take your suit to the cleaners for a pressing as most of them will do a poor job as well; find a reputable tailor and ask him who does his pressing, as the chances are very good that he sends his work out to be done on specialized equipment. Failing that, find the best cleaners in town and have them give it a pressing. A good suit will recover between wearings, and little creases in the elbow, knee and back can be gently removed with an iron and a little steam (use a rolled up towel in the sleeve).
Your suit will love you for it.