i echo everyone else. do your homework. know a little something about every house, so you can ask good questions. try to have something ready to use for each house. i know at purdue that's tough because there are tons of houses. but you've got time.
do you need recs? if so, get the letters in.
bottom line, be organized and then relax and have fun.
you are already showing you care and you should be hugely successful.
now get yourself graduated.
i teach high school and you would be amazed, or maybe not, by those who assume it's a done deal at this point.
mmcat
PS purdue grad. so i've been there done that.