Know how to describe yourself in just one word. Make it a good one.
Wear a suit.
Know how to read a SID, a STAR, and read a surface chart of DFW to determine takeoff minimums by RVR etc.
Review emergency and general procedures for the most complicated airplane you currently fly.
Be sharp with IFR charts, etc.
Have an open mind. Eagle flies coast to coast and out in the Caribbean islands. Smile. Try to relax.
Act like you're meeting a significant other's parents and/or other adult family, and you want to make a good, polite, first impression.
(It sounds cheesy, but that's one of the secrets to my interview success.)