Teen looking for job (Please help and read?)?

My family has been through a lot lately and the bills are piling up. Do any of you have any suggestions on how I can help? I've done a lot of volunteer work, I've cooked, been a waitress, a part time nanny etc etc. I've done things like that before and yet for some reason, no one has called me back to hire me. I'll be 18 very soon, could some of you please tell me what I could do to be more successful or get some money to help my family?