Make sure it is allowed. Post your business cards in an obvious place and pass them out liberally. If your work is good and fast you'll pick up opportunities. Make sure you have a mix also. Don't think you will pick up work only on one side of the track.
All children love face painting.
And most parents like to spoil their kids. As you get more exposure in these areas you'll have money to pay for supplies and a couple small ads. Slowly but surely you'll pick up some corporate accounts which will become your bread and butter. Don't under price yourself and don't get to greedy. Work on your quality first and then your speed.