Locate the manufacturer. Manufacturers usually have their insignia on the saddle. Most are on the left strap holder or on the fender. Some also put it on the stirrup strap.
Look for the model number, this is on the left strap holder or under the skirt. This will tell you a lot about your saddle (size, color, gullet width, etc).
Determine what style of saddle: trail, endurance, show, ranch, roper, cutting, reining, barrel, gaited, mule, draft, trooper, etc. Not sure? View our handy article here.