Who do you ask for a reference?

Some applications require a name and phone number of people. They'll often specify if they want personal references or professional ones.

Sometimes when you apply for a job they'll send you a form that you need to get filled out for references. I've used supervisors from previous jobs, and I've also used instructors.

You want to use someone who is aware that you'll be using them for one thing. That way, they wont get an unexpected call, and not know what to say. If they have time to prepare, they can think of things to "talk you up".

Also- you just have to trust that you've found a person to use as a reference, that you've made a positive impression on.