Hello veterern brides

We are using a caterer for our Sept 2013 wedding and just seeing if anybody had any advice for me. I've done my homework and gotten quotes and made appointments with the 3 caterers off of my venue's preferred list that seemed to be our best fit and they are all within 5k of eachother, but I lose it then.
This is the one part of planning I really don't know a thing about! Every wedding I've been a part of / helped plan has been catered by the venue so this is new to me!
Any advice or basic lists of what I should be looking for? I like to "lay things out" to compare so I just want to make sure I don't miss anything!
TIA!