Diluted in water, this treatment has always been tried and true for me. After washing and conditioning my hair, I use the mixture (about 1/4 cup to 2 cups of water) as a final rinse. It results to a soothed scalp and shiny hair with no lingering scent. I used to do this once a week in the winter especially and had no scalp issues for the entire season.
I consider myself a veteran user of this. I actually make a clay mask once a week for my combination skin type, and I've blogged before how awesome it is for hair. I definitely have focused on my scalp when applying the clay to my hair and it really helps - I actually use apple cider vinegar and raw honey in my mixture which leaves my scalp and hair feeling and looking great!
This oil is magic in a bottle for me. I used to have severe eczema flair-ups when I was younger and my diluted tea tree oil was applied to my skin to clear it up. You really only need a little bit of this stuff because using too much can cause irritation. When I wore my hair straight or wanted a style to last a while but my scalp was itching, I would take a cotton swap with a diluted tea tree oil mixture and dab it on my scalp to cool it off and stop the flaking.
What are you some of your tried-and-true dry scalp treatments?