It needs moisture.
I suppose your hair is wavy or curly.
My daughter's is. And it gets dry, it actually feels dry!
So, after fighting for a good while, I read all google articles about hair.
There is a chart to rank your curl type.
Then, you have to keep the curl/ wave, and moisture in your hair.
I do spray my daughter's hair when brushing (daily). Never ever brush your hair dry.
Then apply an oil ( coconut used to be great for hers, but now that she has grown a bit, her hair has turned drier, and argan oil is working better. Argan oil hair spray is the best, and it makes her hair shiny too). You have to find which oil is best for you.
Apply it when your hair is damp, after washing it. In my DD's case, I even apply it daily when brushing. Her hair can take lots of oil without feeling greasy at all. It is like magic. I do not apply close to the root. Only 1 or 2 inches from her scalp.
There are special products that encourage waves/ curls to form. These you can apply to the hair that you have damped a bit after brushing. They also help to keep moisture on the hair.
There are masks and serums to restore moisture on your hair. Try leave in masks, and leave it overnight. Again, argan oil is great.
It takes a while though. You have to keep going till the hair has enough moisture in the strands, specially if you have long hair. Then it will curl, keep the curls or waves, stay non- frizzy, and shine.
For my DD, I have to do it daily, or her hair gets fluffy, first, and frizzy next.
Also, hair has to be damped daily with a spray for her, and oiled. Still, it never feels oily! Her longest strands feel actually really dry at the ends at present. I have to work on those.
She washes her hair every 3 days or so.
It is so different from mine.
I do have wavy hair, yet it is oily, so I wash it daily. It does not tolerate any oil (even any trace left on my hands will turn my hair into a sticky flat mess)