Some guys will say they can't go any lower. They can. And if they really don't budge, see if they will include some ammo (not reloads) or some other merchandise.

Bring some food. The food there is overpriced and gross.

Keep your eye out for thieves, almost every gun show I've gone to the made an announcement that someone has had something stolen from a table.

Walk around at least twice you will always see something you didn't see before.

Try and take notes of prices.

Don't dry-fire. They will flip their shit.