What type of hair do you have (oily, dry, combination)? Is your scalp flaky because it is oily or is it dry? Most of these things will have an impact on the type of blend best for your skin/hair. What is the pH of your skin/hair?

My mother swore by coal tar soap, my sister by rinsing her hair in beer every couple of weeks.

Keep away from anything that has a petrochemical base (if you can't pronounce the words in the ingredients then there is a good chance it is a chemical base).

Quick suggestions
Bicarb mixed with warm water as a shampoo
Apple cider vinegar mixed with warm water as a conditioner

If you want a lather, then get some pure soap (soap flakes from the washing isle, just make they are 100% pure soap), a bit of glycerine. Soap into a bowl, boil some water (I use purified water), put the water into the bowl with the soap, then add the glycerine, let cool, put into a bottle. Don't have actual measurements at the moment as I'm at work & my notes are at home. Just remember that it will not lather as much as commercial shampoo.