This PDF gives you some guidelines to make your use of them more effective. Though it has some useful tips, the companies cited are no longer in business, but http://www.fontspace.com/ is and below are some of their current fonts that are great for children:
All the fonts above are from: http://www.fontspace.com/ and are free downloads.
Google fonts also has a great selection of free fonts
One very important guideline to keep in mind is to NEVER use the typefaces that have reversed letters (such as a reversed "e" or "s"). It might seem like that would be a harmless, cute thing to do, but when little children receive a printed piece from a respected person in the church and the penmanship is all wrong, it can be confusing.
Have fun, do kid-friendly things, but always remember the position of authority and influence you have in young lives.
To download the PDF, click here or on the image.