Quote Originally Posted by Aerith's Knight View Post
lvling up is the best at the beach near bone city.. you will fight a big bird.. hes the best exp you have now
There's that, and also on the beach near Mideel. You get around 2,000exp and 200AP (get rune armlets and double growth weapons), and 5,000g each fight (sea worm).

A good place to get all those kills for your limit break is in the mythril mines. You can usually get groups of 4-5 enemies that you can one shot with Matra Magic (enemy skill, if you haven't got it just run around Midgar area to get it).