I bought a set of cassets called Komedy Kids Show Kassets, great investment.

You can get on Steve Kissell's site by going to 'comedy magic workshop.'
Look at some of his books and tapes and his convention tour. I've been to a few of them and they are very helpful.
He may have one close to you. Check out his book called Successful Family Entertainment! It's about marketing, Restaurant magic, Birthday's, Stage and comedy bits. I'm not at home right now so I don't have Sammy Smith's site with me. I'll get it out tomorrow. Steve also has Clown derby tours too. They have magic classes and dealers at these too, along with how to put on a show. You don't have to be a clown to go and learn. For those of you that wants to open up a few more doors look into several ways to market yourself.
Get into Clowning also! You'd be suprised how many people wants a Clown at their kids parties. Learn to juggle, balloon twist, face paint- whatever it takes. I've been hired to do all the above for one reason or other. $100.00 an hour these people don't bat an eye at.
I'm a ventriloquist too, you'd be suprised at how much you can charge for that. If anyone is interested in that field go to 'Vent haven .com'
Good luck

I believe Sammy Smith's site is spsmagic.com

I'm surprised nobody has mentioned David Kaye (http://www.sillymagic.com/) Maybe he's not as well-known as these others (which I've actually never heard of), but he's very good.

His book "Kids Show Kliff Notes" is great (as is his lecture on the topic) and he has some other books/lecture notes on his website (under Magic Shop) that seem to be pretty good as well.

As far as Birthday Parties, I learned quite a bit from Trixie Bond (http://www.trixiebond.com) I know she does lectures and those sorts of things. However, she doesn't seem to have any of her books/notes for sale on her website for some reason. There's a link you can use to contact her (go under "For Magicians") -- maybe you can get some info. from her that way.