The most important thing I could and want to pass along on this topic is the incredible significance of truly loving your child's hair.
Second to that is, without question, that moisturizing is essential. Pearl's hair is the tightest, most coarse texture of hair that God makes. At 4C, her curls need intensive moisture to remain healthy and vibrant.
Moisturizing is bigger than just one step in the process. Pearl's hair is very, very thirsty, and we moisturize (and re-moisturize) a few times throughout the day.
Now, the conversation about moisturizing products can be a lengthy one. Every black woman I have engaged in a discussion with (or been approached by) regarding products has essentially told me something different than the last woman or the next. Every single woman, regardless of her ethnicity or hair type, has her very own unique opinion about which products are the best. No one's hair is exactly alike (props, Creator), and no one's favorite products are the same either. Having said that, realize that everyone thinks the stuff they use is the best and only answer to whatever issue you may be facing with your kid's hair.
The reality is that you are going to spend a small fortune in hair products.
To find out YOUR favorite products, you'll have to experiment...try different types of moisturizers/cleansers/styling goos and varying combinations of it all. The smart thing is to connect with other mamas in the same boat and pool your resources. I guarantee you that I have bottles and bottles of stuff that I've bought and hated over the past few years. Hit me up if you want to borrow some of it. Likewise, share and share alike.
Keeping that in mind, below are some of the moisturizing products that I have come to rely on as the best nourishment for my sweet Pearl's curls. They're all Amazon affiliate links, which is where I tend to find the best prices. Sally Beauty Supply carries all but the Carol's Daughter line, but even with a membership card the prices are almost always better on Amazon. Locally, you can only get Carol's Daughter from Ulta or Belk. Target will occasionally run a B1G1 sale on the Shea Moisture brand (I've yet to determine a pattern on that but if you know the secret, please do tell), which is a huge help in building your collection of products you love as well as stuff you want to try.
Remember that these items are just for moisturizing; cleaners, conditioners, detanglers, tools, styling aids...all of those are entirely separate categories.