Do this show at your own risk. It takes longer then a month to put a kids show together.
I have about a month to get ready. What do you suggest?
Cancel the show.
If you're considering doing tricks like Saw, you shouldn't be performing for kids. They will see what you do and try to copy you, the difference being that they don't know the secret and will kill themselves trying.
I realize that you're probably not going to listen to what I wrote and do the show anyways, So I'm at least going to give you advice so that you'll manage to get out of it alive. The first thing you should do is get Seriously Silly by David Kaye
. It is the bible of kids show magic. This is possibly the best advice that anyone could give about doing kids shows.
About doing card tricks, from personal experience, even up till about age 10 or 11 they couldn't keep track of more complex tricks (Biddle being one of them, can't think of anymore off the top of my head). At about age 7-8 most kids know the different suits, but they can't keep track of any trick longer than 5 seconds, unless you're really good with kids. If you have any very visual tricks that you could add a good story to, then kids might be interested in it, although it might not be the right thing for a birthday show.
As to what tricks to recommend, remember one thing. With kids it's all about the patter
. If you can keep them interested, many different tricks will be good. My best suggestion would to think back to when you were a kid and remember what tricks you liked the best, and do those (but to your own patter which is the most important part
) (there's a reason why I wrote that twice with bold, italics, and underline, because for kids, patter is the most important part of the trick
). My kids show is basically made up of tricks that I remember seeing when I was a kid (cut and restored rope, sponges, coloring book, nesting wands, change bag) and I know that since I liked it as a kid, most other kids will also like it.
But all that, and more, is covered in Seriously Silly
. GET IT! You will learn so much about giving shows for kids.