Being put on a college Wait List means that you haven't made the sale. The college isn't sure about you—whether you are the right addition to their next class. So what should you do? Sitting at home and waiting for a college to come after you won't make it happen. Sometimes miracles do occur, but don't wait for one.
You must actively go about impressing that college with why you should be accepted. How to do this?
VISIT THE SCHOOL—and let them know you are coming.
Schedule an overnight while there (hopefully with someone you know who will put you up), if not, ask them to recommend someone.
VISIT CLASSES—find classes which make sense for your intended major and attend them.
Sign your name wherever possible—you want a record that you were there.
ASK FOR AN INTERVIEW—even if you already have had one. Try again, even if they say no. Once you are there, see if you can pop your head into the Admission's office and say Hi.
Write a snail mail letter (which will go into your file) and a duplicate email telling the college 3 reasons why you love their school and what you can do for the school if admitted.
Add any of your latest grades (if good), and any awards, interesting developments, etc. since you sent in your application.
Ask another strategic person to write an "introductory letter" (an alum, person of standing at the college, someone who will get their interest) stressing what you can do for their school (while describing your "who am I" which you have passed on to them).
If you are willing to do these things, you can make it off the List.
If you need, help, let me know.