3c/4a... awesome hair color!!!
Co-washing is using a conditioner like you would a shampoo, ie. washing scalp and/or hair with it. Many people use cheap conditioners like VO5s or Suave to do co-washes. Nice to do in between regular washes to help maintain curls and moisture.
On days you don't wash or co-wash you could use a curl refresher product (one like Kinky Curly Spiral Spritz, I haven't used it, but a product designed to do what it says is what I'm rec'ing
) to lightly mist your son's hair and then seal with tiny bit of oil (or not
) to maintain his curls. In the past I would mix up some conditioner with distilled water, Glycerin and a few EOs and Oils and spray that very lightly onto my kids' hair. Or I would lightly mist their hair with distilled water and then run some conditioner over their hair and then style it. But, I find just plain distilled water + tiny bit of aloe vera juice does the trick for us, then I put some oil on the ends of their hair. I do that between washes.
In addition to what the great ladies have suggested (especially the satin pillowcase, OMG that's been saving our curls and cutting down on tangles),
Maybe try Camellia Seed Oil or Avocado Oil to seal in moisture and help control frizz. Both oils leave my kids' hair soft and aren't greasy or heavy as the hair absorbs them well (and I use small amount
). But, too much of those oils plus a good conditioner can make hair way too soft, so gotta use small amount. Coconut Oil also helps with frizz, but, with my kids, it also tends to make hair bit tempo-straight if use too much.
California Baby Super Sensitive Shampoo and Conditioner have been great for us. I also use the conditioner as a leave-in on bottom half of hair and then seal with Avocado Oil on the very end of hair and on areas that tend to get frizz and sometimes follow that up with Aubrey Organics Mandarin Magic Hair Moisturizing Jelly.