Tips

I agree that the key to getting good tips is your ability to entertain.
I used to busk in Central Park in NYC. There are A LOT of people there doing balloons and they are basically what I like to call balloon machines. The same thing over and over and they get maybe 2 clams. They don't interact with the children unless the children talk to them.
In my conversations with them they tell me that during an eight hour day they'll make about 150 clams. They don't do it for the love of the art or the love of children. They never learn anything new. They are just in it for the money, which is ironic.
I, on the other hand, love to work with children. Dealing with them keeps me sane in this ever increasingly cynical, hypocritical world. People tell me I'm a funny guy. They laugh AT me in any event. The point is that by being entertaining and interacting with the kids I consistently made 200+ clams in 5-6 hours and I was just doing it for some extra cash, ( I had a good job ) and to have fun. I probably used 1/2 the balloons the others used. Many, many times I would get a 20 clam tip for a 4 balloon sculpture simply because the kids had so much fun. I also got a few gigs booked on the spot when I wasn't even looking to book any.
It really isn't so much what you do, though skill is important, as how you do it. Balloons by their very nature are fun. The person making them should be also.