How can i get my hair to grow more?

ive have a medium afro that i started letting grow in december. it has grown alot since then also i noticed it grew this month also. i am trying to get braids but the other day i wanted to get it braided but it wasnt long enough. i wash my hair once a week becasuse i heard it was bad to wash hair everyday and i use oil sheen. what else should i do?