Never forget to invest in your partner's haircare! I've been lucky and managed to convince my gf to grow her hair out to at least waist length and we're trying out which shampoo+conditioner+hair oil combination is the best for her hair texture, and the recent one we tried ended up making her hair so much softer i ended up savoring the amazing feeling of her soft tress on my dick much longer.
Hair thickness do also played the part and generally the less split Ends also makes it better.