Where do you usually go to level up your Limit Breaks?
Possible (SPOILER) (I don't know if you'd call any of this spoilers, so I'm just being safe) I usually get to the part where I get Vincent, then travel back to Fort Condor and fight in the forrests around there. The fights there have 2 (rarely), 3, or 5 enemies at a time, and by then, one Matra Magic should get rid of them all (with an occasional miss here and there). Then, after I've gotten all of the first parts, I go back to Cloud and Tifa's hometown (can't remember the spelling) and fight until I get those purple demon things with wings, manipulate them, and have them attack whoever needs to use his or her limit break to get the second parts of their limits. Then, after I get Cid, I do it all over again (it's good for gaining money and AP that early in the game).
I'm playing it over again, and that's where I am in the game right now, and Cloud is already at level 33 with Meteorain (two or three more uses to get Finishing Touch).
P.S. For those who don't know, you get the second parts of limits by using the first part 8 times, and you get the next level by defeating enough enemies (it varies between characters).