I was in your position just a few years ago, and the one thing I want to add to this thread is that online applications are useless. I went door to door down Whalley the day school got out for the summer and eventually ended up working at McDonald's that same day. They didn't interview me, all they asked for was the earliest I could start. You just have to be confident enough to approach people face to face, maybe ask someone working the register something like "Do you know if you guys are hiring? Is your manager here so I can speak to them?"