There are lots of braiding styles out there for all types of 'afro' hair. Some of these are safer for kids' hair and simple enough to do at home. However, there are also some styles that take a lot more time and expertise, but have incredible results.
This Pinterest has a brilliant collection of kids' braiding pictures, along with twists and natural styles. It's a great source for ideas:
http://www.pinterest.com/lisabhookinitup/love-the-kids-braidstwist-and-natural-styles/
This slideshow also shows a big range of braiding styles:
If these pictures have inspired you, here are some hints and tips on how you can achieve these styles yourself:
Simple braiding styles
You can find tutorials for almost every hairstyle under the sun on Youtube. There are plenty of braiding tutorials that show you very clearly how to do the basic techniques, like this one:
This braid can be the start of many hairstyles, so it's important to practice before trying something more complicated.
Looking after kids' hair
It's really important to look after young hair, as it's still growing. Any damage done at an early age may affect the hair into adulthood.
Some styles specify that they are 'protective', so if you're worried about looking after your hair, these are a safer bet.
More complicated braiding styles
If you have a natural flair for braiding, or a good hairdresser, there are some really cool braiding styles that you can try. Even if you're just starting out, with lots of practice these styles are possible.