Make sure your resume is up to date. Do your homework on jobs before you apply. If you're nervous or unsure about questions, do mock interviews with friends or family and even look up online for additional questions to ask the interviewer so that you have as much information as you like about each job before you leave. Also, don't forget to ask at the end how long the wait will be for you to hear back from them. That's a common mistake I'm seeing from others on here is they forget to ask that and end up asking here instead - which doesn't do them much good.