Do not busk in a mall. No reason to. It's legal to busk pretty much everywhere in Boston except ... a place .. the name of which I'm totally blanking on. But it kind of sucks to busk there anyway, because they schedule you and all that jazz. For that place you need a license (given by the people that run it) ... gah it bugs me when I blank on names. Stupid OCD.
Casey had good points. I would add: Learn some hat lines. If you want to be fairly sure about making money, ask for it during your set. Keep your set short and simple. If you've never busked before, 8 minutes may be all the time you can hold a crowd's attention. What I do is create a modular set of routines that can go for up to about 20 minutes. Get a table. I got one at Target for $15 (folding 'activity table') and it easily tripled the amount of crowds I drew.
Plan out your routines with some 'core' tricks. My only 'cores' are the opener and closer. Use your opener to draw a crowd. It should be visual and also modular. Once you get one person to stop, more will stop. Invite them closer, try to catch more people's attention. If the crowd is really digging the show, use some of the 'extra' routines you have prepared. If they're just kind of hanging on, go for your closer. Make sure you tell them you work for tips. There's tons of hat lines out there, you can probably Google for good ones.
As Casey said, always be polite. Always tell them your name. It's great to be recognized as, "the magician" but it's much better to be recognized as "(Your name), the magician!"
Confidence is key, as mentioned. When you're a busker, you have to believe you are the best thing since sliced bread. Don't be a jerk, but project confidence.
