ctor know thyself! In the street you might be asked almost any question. "What's your name?" "Where do you sleep?" "Why are you carrying that enormous rotten fish?" You'll never memorize answers to everything, so you'll need to improvise them. This means you need to know yourself, your character, to invent reasonable responses.
Your character is a framework to support your ability to improvise. Don't get hung up on inventing some complicated backstory that would take hours to explain -- sadly, you're the only one who cares. Instead, invent some plausible general facts about yourself, your life, and why you are present at the Faire. Everything else can be invented on the fly. Keep the things that work, discard those that don't, and remember that the customer has no idea what you told the last customer.
You, your character, needs to have the basics and it will be easier for you and your fellow actors if these are consistent.
More detail is better (Elizabethans loved to talk) and everyone still likes the unlikely and outlandish. Far better to say that your sister almost married a hog farmer until she accidentally fed the hogs rat poison, than simply that "I hae me a sister." You are the storyteller of yourself: make it up and keep it if you like it, discard it if you don't!