Finding it hard to study and find a job?

I have just recently quit my full time job as to find a casual/part-time job to suit my uni timetable.
I did not think it would be this hard. I have handed in resumes everywhere. When I was younger I would get a phone call later that day. But now that I'm older I think it is a bit harder, it is the next day since I handed out resumes and I have had no phone calls as of yet. Hopefully I will soon.
I think a handy tip would be to make yourself appear available all the time and then once you have the job set your boundaries with the manager.
Don't aim too high as well, I have just been handing resumes into shops where I think it would be easy to work in. As once I have finshed work I want to forget about work instantly and then go back to studying.
Always be orgainised and ready to answer any questions that are asked when in a interview.
Make sure they know that you do need time for study around your classes.
All in all study comes first and then you can worry about work after.
The big picture is about getting your degree/diploma or whatever and going into the career that you have been working for over the last 3-5 years. Therefore I want all my focus to be on my study, not my current job.
Anyway thanks for listening.