Is there something you can do to make your hair become thicker?
Tthere are certainly things you can do to not "damage" your hair and those things are avoid harsh chemicals, avoid the chemicals that are often found in coloring agents, treat your hair gently and avoid traction ie pulling on the hair shafts by pulling the hair back, used soft gentle approach to brushing with wide tooth combs, do not over wash, do not over condition and do not over treat with hair products, sprays, and gels. From a medical perspective, if you are concerned with a possible hair problem, thyroid and some dietary abnormalities can predispose to hair problems. So, if you are concerned that a medical explanation might account for hair abnormalities, I would suggest following up with a dermatologist.
There are a few treatments that help thicken existing hair. Using Finasteride daily. Applying Minoxidil 5% daily. PRP/Acell treatments as well.