A loupe, reading glasses, a notebook with paper that you trust, some take a small maglight to shine into pens.
A bottle of ink, not all vendors have ink and paper for testing pens, and some may object to you testing pens - if so 'walk on by'. A rucksack so that your hands are free, and some are very very warm, useful to stuff a jacket into.
Some shows have a communal area and tables where you can talk to others and share stuff, so its nice to take a more unusual pen with you to allow others to use.
My father keeps a journal for pen shows, inks and pens he has tried, people he has met, who specializes in what, business cards.
If you have a spare pen or spare ink, take it with you, perhaps swap with someone.
Take a pen case with you, some sellers just hand the pen over to you, no bag, box or anything else, so you need something to keep the pen secure.
Some sellers have a show special, a new pen that is heavily discounted for the show, the last pen show I went to, one seller was selling new Conklins for $10 if you asked him, same man the previous year was selling a Conklin display case for 20 pens for $8.
Edited by Parkette, 01 February 2018 - 07:07.