After a decade+ of doing faires, My best advice for any Faire goer just starting out:

*Have a good head covering

*It is historical Theater, not Living History... have fun with your garb

*Dont load yourself down with so many weapons and accoutrement that you will be uncomfortable or feel like a pack mule

*eat and hydrate... Salty snacks before hand will help your body retain water. Having a good mug is very crucial to staying hydrated and still maintaining the illusion.

*Have fun and dont take it too damned seriously.