Don't have a Citabria POH with me now .... but I think it recommends against slipping with full flap. No idea about Cessnas.
As some have said it's a great way to lose height if needed on approach. But it isn't something to go out and try yourself. Get some instruction and take it from there. Don't get talked out of doing it by inadequate instructors. If the aircraft can do it SO SHOULD YOU!
Once you've got slipping on approach sorted out, another challenge is to slip through a 180 degree turn with the aim of being at a certain planned position at the end of the turn. Practice left and right.
Good luck