Combine your regular shampoo with a little bit of baking soda and a splash of water to create a thick paste. Apply the paste to your scalp and leave it for a few minutes. Rinse your hair with water to remove the paste and then wash it as normal with your regular shampoo. This two stage wash should remove all of the grease and give your hair extra volume.
Noteworthy-- 10 parts water mixed with 1 part apple cider vinegar, apply to hair, leave 2-5 minutes, rinse. This can be done between shampoo & conditioner for normal washes or before conditioner for co-washes