semen definitely doesnt help. I used to cum in my wifes hair every other day for over a year, dont think it helped at all.
Now I am away from home and I dont get to cum often and its usually once in 2-3 months depending on my schedule and taking care of the baby.
all I can say is it is better than before. so, oil massage and hairwash alternate days, keeping scalp clean definitely helps.
No straightening or coloring!