Go with the 23's until you're a solid single digit-----23's are a great club
Kind of depends on if you have some solid fundamentals set and how you prefer to learn. I dropped from a 25 to a 15 by going with a less forgiving iron (Cleveland TA5's to Cobra Forged SS to TM RAC MB's). Using less forgiving irons forces you to pay attention to your swing a little more and give you more feedback about your misses. Since the TM MB's I've since moved onto Mizuno MP 33's and continue to improve. A lot of the slop in my swing has tightened up and I'm a lot better off the tee than ever. I plan on dipping into the low teen's this year. The MP32's are supposed to be more forgiving than the MP33's.