I co-sign w/ everything Melanie M told you. I have two girls, ages 6 and 9 and we all have natural hair. The only product I would add is a leave-in conditioner called Cantu Shea Butter. It is only $4.97 at Walmart and our hair loves it, but I seal in the moisture w/ an oil. Walmart also has this oil that is pretty cheap but good called Herbal Oil for $1.97. I seal the girls moisture in with that and we are good to go. Just don't add anything else to that leave-in b/c it does not play well with things that are not oils. In the morning after I take off their little satin bonnets, I spritz their hair w/ a mixture and seal w/ an oil. A less expensive spritz you can use is mix some conditioner like Suave Tropical Coconut conditioner w/ water and extra virgin olive oil or glycerin. This works good on my kids hair, but all of our hair is different and responds differently, so trial and error is a must.
Another thing I would suggest is to try to keep your child's hair in protective styles because that tends to keep the moisture in also and lessens breakage from unnecessary manipulation. Some examples are two strand twists, box braids or plaits, etc. I am not a huge fan of braids that are flat to the head because there are a lot of people out there that pull the hair too tightly. And stay away from products were petroleum or mineral oil is used as the first ingredient.
I co-wash their hair about 2-3 times per month and then do a real wash w/ shampoo once every 4 or 5 weeks. Some people wash w/ baking soda and rinse w/ apple cider vinegar, but you will eventually get to that one day. Play around and try different things first. I am what they call a recovering product junkie because I have tried quite a few things, but now I have found what seems to be working for us now and I will stick to it until it stops. lol