Hands in the mouth

MamaSquishyB

Levi is constantly sticking his fingers in his mouth and chewing on his fingernails.  How do I get him to stop?  I feel like I'm constantly saying, "Levi, hands out.  Levi, get your fingers out of your mouth.  Levi, STOP CHEWING ON YOUR FINGERNAILS!!"

Besides driving me nuts, it's so not sanitary and I know it won't be appropriate once he starts preschool in a few months.  Any ideas how I can break the habit?

Thanks!