Target market question

I have postcards designed and ready to print, but I want to get some feedback before I order. I already have my name out there for Birthday parties and that part is going well. I want to branch out into sponsorships. I want to do festivals and such, but not ppf. I have an idea of what type of places I want to target but If you have better ideas, I'd love to hear them. I was planning to send to PTA's, Boro's, Event Planners, Corporations, and Political Organizations. (not at the same time...) I will have a slightly different message for each. Are there any certain types of businesses that you have found are more likely to sponsor a face painter at a festival? I don't want to beat a dead horse and market to people who won't bite. What is your experience in who responds the most to your postcard mailings?