How much credit is needed?

They tell me I'm a "non-traditional" student. 27yoa and want to enroll in an aviation school. I have a credit score in the low 600's. When ever I ask about student loans every one just says "fill out a FASFA". I'm tried of hearing this. Is there any one who can tell me how hard it is to get a student loan? There is a slim to none chance I'll be able to get a co-signer. Which lender is better then the other's? I'm not putting a lot of hope in schoolarship's and grant's; there arn't any for some one like me. And do'nt tell me to fill out a fasfa. When I did they told me I was'nt eligable for any help. I guess working and paying tax'es all these years is'nt factured into the fasfa. Thanks for any help.