I used to be a GSA before getting promoted so I can help you out here! Okay it's not always easy to tell who is a GSA or GSTL just by looking at them. So when you get in look for a team member who is not with a guest and tell them it is your second day so you don't really know anyone and ask...
Here is my advice. Work your butt off. Do everything you can to make a name for yourself and get recognized. When they call to see if you can cover a shift, do your best to get there, even if you can only cover part of the shift. Always come to work with a positive attitude and try your best...