How Exciting !!
It depends on what you enjoy doing at events... I like to see and are amazed at all the creativity that goes into whats being shown, the ideas I've never thought of, these events always seem to inspire me. Most of what I'll never do myself.
If they allow take photos of somthing you see to recall later, graph paper if somthing simple.
I buy some but never much, unless you have something absolutely can't find a match for, take a swatch. may run across it. May be collect buisness cards so you don't have to carry bought goods?
Great Walking shoes a must, a bag big enough to carry your goodies, If you do shop.
Relax and enjoy the day around people who enjoy the craft as much as you do !!! Have fun talking to other quilters. :)