I hope some other folks will chime in on this one. I noticed there were some questions about equipment for busking...so here's some thoughts:
First, check out what's legal where you'll be playing. Many areas require permits for street performers, or performances may not be allowed. In some places, New Orleans, for instance, the fines are mutha dog. Many areas allow acoustic only. You might be able to stretch that with a Pignose or a Microcube that isn't turned up too much, but a Roland Cube 60 or a Twin Reverb will get you popped for sure. Volume is a problem, out of doors. Try for a doorway that acts as a megaphone, use a 12 string or a resonator if you can.
Keep it simple. You're out on the street, and it's very real and very random out there. The less gear you have to keep track of, the less likely it is to take a mind to wander. Doesn't hurt to be able to pack up in about 1 1/2 seconds and run, if it comes to that. Children are mindlessly and randomly destructive. A 2 year old doesn't mean to run blindly into your guitar stand, but they do it, and Daddy probably isn't even gonna try to replace your smashed guitar. Likewise, if a number of gentlemen in matching attire carrying various implements of destruction request the loan of your instrument, you gonna lose. Even if you've got your old friend, Mister Browning, along, (and that's a bad idea for a whole lot of reasons) there's no way to win this one. So you don't bring the 1961 D-28 your father gave you just before he died. What you need is, loud and cheap and easily replaceable.
Do try to have fun. Just like a bar band, folks are gonna respond more if you're up-tempo, and you look like you're having a good time. Try to have some patter, some come-hither lines to bring em in, and some patter to get them to tip. Make it kinda funny and interact, this isn't a concert, you're entertaining.
I'm sure there's folks her who'll chime in with lots of good stuff