paint works better, but make sure its not the kind that rubs of when it drys. nail polish works ok, but 你 should use a paint brush with nail polish too!
你 can use: Nail Polish Acrylic Paint 或者 Model Paint. Either one will work. 你 can even use spray paint if 你 want! Remember, it's your personal pet, so 你 decide what 你 want to use. Any of the ones listed here will work perfectly. 或者 你 can come up with something new.
I am most familiar with using nail polish. 你 can ask me anything about that, if 你 want.
Also 你 can go to YouTube and 搜索 Custom LPS 或者 something like that. Also, this video is of MY customs and what I used. Look at that if 你 want: