Wash
Lazy Method
Once or twice a week. Shampoo and conditioner. But the trick with very long hair is to wash it in sections, since roots need more cleansing while ends need more moisturizing.
Before I wash, I "stritch", i.e., scratch my scalp to dislodge any dirt or flakes.
Then I shampoo the roots twice. Once by itself, and again with the rest of the hair. Each time, I scrub the scalp and then lift the hair with my fingers so that water can reach the scalp when I rinse.
I horizontally divide my hair and condition hair below the shoulder for a couple of minutes. Then I apply conditioner to the roots, work it to the rest of the hair, and rinse.
After my hair has been towel tried, I spray leave in conditioner on the ends, then comb it through the whole hair.
Fancy Method
As I would with conditioner, I focus oil on the ends and only lightly touch the scalp. Though I will apply oil to flaky trouble spots, such as at the temples, which are prone to tinea versicolor after a sweaty workout.
The bottle says to let the oil sit for at least half an hour. Some Indian women let it soak overnight. I compromise on an hour or two. I apply it after breakfast and shower when the coffee kicks in.
To rinse, I first coat my oiled hair in conditioner. The oil binds to this conditioner. I rinse out the conditioner and first pass of oil.
Then I shampoo, rinse, and shampoo again. As always, I scrub my scalp and lift the roots with my fingers so that water can directly touch skin (if I don't vent roots, water only touches the outside of my thick hair).
That gets all of it out. My hair is left as soft and detangled as it would be from the standard Western shampoo and conditioner. But it's also lighter and cleaner.
I leave my hair down for the rest of the day so it can dry.
At bedtime, I put my in a simple braid or top knot to sleep in. This reduces wear from rubbing between me and the pillow. Other women achieve this with silk bonnets.
The rest of the week, I wear my hair in a French braid at the gym, or in one of these updos. This reduces dirt and sweat.