Friday is the day for best selection. Saturday is the day when you might get a bit of a deal later in the day. (But if you mis-time your offer on the remaining deals, you also might go home with nothing!)
Unless you are buying from one of the dealers that will be there who might take a cc, bring cash! Most of the private sellers will not take personal checks, cc, or various digital forms of payment. Especially from somebody they don't already know.
If you are a newbie, know how to work on the game you buy, be willing to learn how to fix it, or have the phone number of a good repairman in your area. Whatever you buy will eventually need to be fixed. Maybe a year later-maybe the next day.
Pinfest is a lot of fun. There will be many games there for sale. Some good, some less so. Keep your eyes open and you will learn a lot while enjoying yourself. PS 90's B/W A list games are getting expensive! Looking for a "solid deal" is a very relative term. A nice A list game could easily run 5-9k, depending on condition!