Keep it simple, 65 knots suffices quite happily for the 172 on the approach and then flare, flare flare! Get that yoke back!!, all the way!!, and wait for the stall warner, dont let it down til its whistling at you! You've got to git rid of airspeed! Try flying some tailwheel, that'll teach you to hold off landings. People will give you all sots of theories, just keep it simple, a 172 just like a pa28, piece of cake