Full costume is a must!
may as well go all out if you're going :D i'd cosplay at a convention if i went
I wore the kilt and puffy shirt a few weeks ago... go for it. It adds to the fun.
You usually get free entrance for full costume dress
Go in costume it adds to the gayety of the faire. Have fun and you will be so much more into it and so will other people that talk to you. Being a on looker is never as much fun as being one that everybody is looking at. Don:t be a wall flower. Whenever my wife and i go to any kind of theme party we always try to go with the theme as much as we can.
If you do, try to get something that is really from the Renaissance era. Too many people at those things are dressed like it was still the Dark Ages.
I've only been to one but I go the impression that a lot of the people weren't really very well informed on the Renaissance period. But the, I have a history degree so I shouldn't expect everyone to know I guess.