Here are some hints for Super Mario RPG. there's a a lot of em! Please send hints here. Enjoy
A great way to get frog coins, go to Land's End and play the "Sky Bridge Attraction" and take the expert course and keep doubling the score til you get 4 frog coins. Now you just got 4 Frog Coins for five coins! It will take a while before you get really good.
Another way to get easy Frog Coins is to go to Land's End and fly the Seargant Flutter course and beat it under 10 seconds and you'll get 5 Frog Coins.