How good does my credit have to be to get a student loan with out a co-signer?

I already have a loan with Sallie Mae and Citi Bank that my dad co-signed for when I was fresh out of high school a few years ago, I want to go back to school after having my twins. My credit isn't the best but I really don't want t ask anyone to co-sign for me. Does my credit have to be great to get a loan for 29,000 bucks.