Bring a camera. I always seem to forget mine, then wish I had one! Just don't take a picture of every quilt or you'll spend the day looking through a viewfinder; take photos of just the very special quilts that appeal to you.
Wear your most comfortable shoes! My feet always start complaining before I am done.
Slip a thin notebook and pen into your handbag so you can jot down notes about vendors. It's easy to overspend on vendor items while you're at a show. Sometimes it's better to jot down the vendor's name and the item you're interested in (especially if it is a specialty ruler or other specialty sewing item), then get online at home to read reviews before purchasing. I have a few specialty items purchased at shows that have never seen the outside of a drawer at home.
Set aside some money for drinks and snacks; helps me last longer at shows.
Oh, and *make sure* that strollers are allowed at the show before you go! They are usually fine at smaller shows, but large shows sometimes ban them.