As a patron, you may dress however you'd like. You might want to take into account, however, that many Faires take place in the hot summer months, so hats and sunscreen could prove useful. If you'd like to attend in costume and you have a full-blown Renaissance gown or suit of armor to wear, you have what you need. Otherwise, get into the spirit of the event by wearing shoes, boots or sandals made of leather; a loose, flowing shirt; and a long skirt (if you're a female) or slim pants and a vest (if you're a guy). For an even more costumed look, attend as a magical fairy (complete with wings) or a court jester in bright colors or "motley" and a signature jester's hat.
No requirement exists to go for a "Ye Olde English" sound. However, it adds to the spirit of the event if you attend the Faire prepared with a few useful phrases. Try adopting "Hail and well met" instead of saying, "Hi, how's it going?" Use "aye" or "yea" instead of "yes," "nay" for "no," "wherefore" for "why" (not "where") and "prithee" or "pray" for "please." Instead of asking where the bathrooms are, try inquiring, "Where be the privies?" If you'd like to know the time, ask, "How stands the hour?" You can even approximate the familiar "What's up?" with the phrase "How now?"
Expect foods that are fanciful renditions of fare from the Middle Ages. Carrots, for example, might be presented as "dragon toes." Inquire about the "real" ingredients of any imaginary-sounding food if you have a concern about taste or allergy. You'll likely find plenty of food you can recognize by name, however. Look for vendors selling sausages, bread, cheese and skewered roasted meats such as chicken or beef. For a sweet tooth, you'll likely find sweet cakes and cookies, such as gingerbread men, sweet rolls and brownies. Beer was a staple drink of the Middle Ages and Renaissance, so expect to find it available for those of age. You'll probably also find cider, tea and lemonade.
Attending a Faire is largely pointless if you'd rather not be bothered talking to the actors, musicians, artisans and food vendors. Interacting in the historical environment is the essence of this event. Try engaging the artisans about their work with questions that allow them to explain the process of their art or craft. You can really invest yourself in the atmosphere if you invent a character for yourself straight out of the time period, telling those around you that you're looking for a "fair, young bride" or are in search of "a new cook for your castle." However, if a performer attempts to engage you on the street and you'd rather not participate, just shake your head politely and continue on your way.