Make more and stop worrying about it!
Okay, so that was a bit of a joke there.
:P
So, with that said, here's another:
When feeling the urge to create another character, take two aspirin or tylenol or ibuprofen or whatever, and lay down for an hour or two. If the feeling persists, then you probably should create the character... ;D
Feel free to add your own silly 'tips'!