Having issues obtaining a credit card?

I am 21, not a student, no monthly or steady income, and I need a credit card to build up my credit. I need something with no annual fee. I've been denied by Chase, Capitol One, Target, Sears, Kohls, Home Depot, etc. I contacted my Bank of America. I sat down with the financial lady and she was no help. She suggested this card and I was instantly denied and she said there was nothing else she could do. When I was 16 I got cards in the mail 24/7 calling to activate, but now at 21 nothing. What can I do?