Other folks here will give you fine advice on the particulars of the attire. I offer this. Put together a ensemble that you will be comfortable living in for two days (in case you have so much fun you don't leave.) That means focusing on durability and being repairable.

Other faire goers I know pick a persona that fits who they are. Soap makers take their goods and materials to make soap with them, musicians take instruments, etc. Think of the professions of the period. Are you a tinker, candle stick maker, baker, Indian chief? The idea is also to have fun with other like minded folks, why not be the person you are in present day that is visiting a past era.