I have very long, thick hair that can quickly turn dry if it is not well maintained. When I put on the hijab I discovered that it also doubles as the most effective hair conditioning mask I have ever used.
A nifty trick that works a treat for dry, damaged hair:
In the morning brush a good amount of olive oil into dry hair, making sure you get rid of all the tangles. Plait it and then twist the plait into a bun. Wear your hijab as normal during the day and discover beautifully soft hair when you get home and take it off. It really does work, and works exceptionally well in hotter climates.
I also plait my hair with a small amount of olive oil before bed so it's nice and soft in the morning. This works well if you don't wear a hijab but I've found that there's something about covering the hair for a few hours that actually makes the technique work much better.
Hope this works for you if you're having trouble with dry hair!