Hi AOPiLaLa
I can definitely help you out with this one. I've been working retail since I was 16. I began at Miller's Outpost, during high school, then got hired with Dillard's during college.
Here's the thing, the smaller chain stores such as Miller's Outpost, now known as Anchor Blue, as well as J.Crew, the Gap, Banana Republic, etc. do not offer competitive wages. Well, not in my opinion. My sister used to work for Banana Republic and my sorority sister used to work for Gap, so I have some idea of their wages.
Therefore, either do the waitress thing since you'll probably make more money and have the option of more flexible hours, or do an upper end department store such as Neiman Marcus, Nordstrom's, Dillard's etc. Of course, you're not going to be rich, but I sure felt like I was when I left Miller's for Dillard's.
It's funny b/c I've worked at Dillard's my entire college career. Now that I've graduated there's noway that I'm going to leave Dillard's for some office job in psychology that will cut my income anywhere from $2-$5 an hour. It's how they (department stores) suck you in. I just see it as a way to push me to find an even better job and of course, continue school.
Hope this helps.
You can email me if you have any questions about the retail thing.