A simple way to level Creature Capture while saving gold!
Leveling Creature Capture Quick Guide
To save gold, simply buy only creature bait, then go to the highest level area you have discovered and spam pet bait. Higher enemies grants more xp I'm pretty sure and you will get a lot of levels that way. When you are happy with your level, you can then start buying traps to select which creatures you want as your pet.
This has saved me a ton of gold because I was doing the typical bait then trap then food then trap method but it cost so much gold!