After being a Midwest magician for nearly 25 years, I've gained a lot of experience in both performing and in managing audiences. I've found that there are certain things that you, the librarian, can do to help make sure that my performance goes smoothly.
First...advertise. Let people know I'm going to be there. Put up posters, hand out flyers and talk to people about the show. Build a feeling of excitement. If the people who come to the show are excited, it raises the energy level of the room and that leads to a better show. Many libraries I work with actively invite nearby child care centers to come to the Summer Reading Program. The child care providers like it because it's free or low-cost entertainment and libraries benefit because more people are coming into the library and it exposes children to the library at a younger age.
Secondly...Make sure I have enough space. I can work in a cramped environment, but if I have room to spread out, the show is much better. If I can get an area 20 feet long by about 10 feet deep, that's great. If you'd like to put tape down to act as a "Do Not Cross" line for children, that's fine with me. But don't feel it's necessary. I have certain tricks up my sleeve when it comes to audience management and I can usually get them to sit where I want them too. Along with that, if more and more people come and we need the audience to scrunch together, I have fun ways of making that happen too.
On occasion I've gone to libraries (and schools) where the adult in charge almost issues threats to the children to make sure they behave properly. They tell the children to sit still, don't talk, be quiet, pay attention, etc. Believe me, I appreciate this...I really do, but for the type of show I do, I really want the kids just to be kids. I can assure you that I will have their attention and that I have certain methods to make them stay seated or be quiet when I want them to or to give me loud reactions when it's appropriate.
On the other hand, there are times when I may need you to intervene. At least once or twice per year I have a 2 or 3-year old just wander up to where I'm performing. I usually make a joke about making a kid appear and a parent comes up to get the child. However, every now and then the parent isn't there. They're in the library looking for a book or in the hallway on the phone or someplace else. In that case, your help is greatly appreciated. Something else that is very much appreciated is some assistance at the end of the show. Sometimes children want to meet me and they "rush the stage", so to speak. I may be trying to get some very delicate and/or expensive props put away and out of reach from curious hands. I try to get the children to back away a little bit, but sometimes the mob mentality takes over. If you see me in a situation like this, please help me out by assisting with crowd control.
Also, please stay in the room during the show. Not only will you have a great time, but it's also for safety reasons. In order to become a leader in the Society of Young Magicians, I was required to undergo a background check. I know I'm safe to be around and you know I'm safe to be around, but parents probably don't want their children left alone with a stranger...no matter who that stranger is. As a father, I feel the same way. Having at least one additional adult in the room is always beneficial.
Finally, if you enjoy my magic show, please tell your fellow librarians about it. This helps everyone. The more shows I book, the longer I can keep my prices down. This especially holds true for libraries outside the Omaha area. If you can help me books shows at several libraries in your area on the same day, I can afford to give you incredible discounts over the what I would need to charge if I just came to your area to do a show for your library.