Sorry for such a late reply! I've been so busy with life.
Tips would be
1. Prepare for generic grad school interview questions. I was asked what qualities I have that could benefit the program, how I would deal with conflict or disagreement with fellow students and mentors, how I would balance extracurricular activities and school, if I had specific populations I wanted to serve in the future....there were a couple of more but I cannot remember. I didn't receive this question during the UNT interview, but my professors and a mentor of mine did tell me to really prepare for the strengths and weaknesses question.
2. Know what you think you can offer the program and look into some of the professors and see if any of them have similar areas of interest as you.
3. Come with good questions you want to ask the faculty/grad student who is interviewing you. It shows that you are interested and makes good conversation.
4. Cheesy but BE YOURSELF. The thought of an interview is scary, but they aren't trying to make you scared. You'll see that as soon as you walk into the room or answer that skype call, that they are friendly and want you to be comfortable. Don't tense and be hard on yourself. You'll do great.