Here's what you'll need:
Vinegar + Essential Oil Hair Rinse
1/2 cup water
1/2 cup distilled white vinegar
10 drops of an essential oil of your choice
An 8-oz. container
Add the 10 drops of essential oil and a little bit of water to your bottle. Mix together. Pour the rest of the water and the vinegar into the bottle. Shake to combine. (Heads up: After shaking, the mixture should settle out and be clear).
To use, shake up the bottle and pour some of the mixture over your scalp after rinsing out your shampoo and/or conditioner. Massage the mixture into your scalp. Let the solution run down your hair, adding a little bit more to your ends. Do not rinse, but feel free to squeeze out the excess liquid.
Depending on the length and density of your hair, this should last you at least 5 uses (for the sake of comparison, I have dense, bra-strap/mid-back length hair, and I can get about 5 uses out of one 8 oz. bottle).