African American hair care?

I am an African American woman and I really need some advice on how to care for my hair. I have short, thick, relaxed hair. I relax my hair every 6 weeks however I only relax my new growth. Now I'm just not sure how often I'm supposed to wash my hair inbetween relaxers. As of now, I only wash my hair 2 or 3 times between relaxers. I plan on trying hair one conditioning shampoo as well as an avocado pre poo in order to keep my hair moisturized. Are there any other products you can recommend? Also, could you help me out with deciding how often I should wash my hair. Keep in mind that after I wash and blow dry my hair, I straighten it with a flat iron and normally straighten about 3 times a week. Thank you so much for your help!