Perhaps it's a difference in lingo but surely you're talking about a "forward slip" (used to get the plane down quickly without gaining much speed) as opposed to a "side slip" (aka the wing down method for countering the effects of a crosswind).
If you are at all unsure, practice slips with your instructor as much as possible (perhaps from 3,000 to 2,000 and then, when comfortable, closer to the ground). Don't do anything solo unless you are very confident of the situation. If your instructor is not teaching them effectively, have a flight with another instructor (this is good to do anyway from time to time as all instructors have a different approach and might impart knowledge in some areas more effectively than in others).
In a 172, perhaps one of the most effective ways of getting out of a slip is simply to release pressure on all of the controls. Assuming you are roughly trimmed for the attitude you want, the plane should recover pretty normally.
If you're solo and find yourself too high and are not 100% comfortable with slipping, keep it simple and go around. Sometimes it can be a bit unerving judging height when approaching a strange airport or when doing a strange circuit at home.