I scratched your back, but I'm still itching!

There is definitely something to be said for doing things for others without expecting anything in return, but at what point do you stop before becoming someone's doormat?
This new job, it's working ok, but I am definitely not going to be here forever. With luck, I won't even be here past the summer. I'm concerned with where my life is going. I'm having the same feelings about my current job that I had towards the end of my time at the Deli. I am considering a second job, but at the same time, I'm also wondering how much longer I can take this one. I could always go back to the Deli, but I am afraid it would be more of a step back than a step forward. Right now it seems like I am having no financial luck right now whatsoever. All of my money goes to bills, and the little extra I can make on the side with tutoring has come to a standstill. Any suggestions? I'm thinking bartending on the weekends....