Test The PH

One way to figure out if a product is good for your skin or hair is to test the PH level. The test range is from 0-14, with 7 being neutral.  An example of a neutral ingredient is water. This test is to see how acidic (0) or alkaline (14) a product is. Our hair is acidic and tests at a 5, so any number close to this would be best, around 4-7. Most shampoos are a seven and chemical dyes tend to be around 8-9, thus the damage. You can test the ph of your products and recipes to see if they are safe by using ph strips of digital ph monitors. I got mine from http://www.theherbarie.com/.

I see that some shampoos are testing at a 6-7 and they dry my hair out, so I probably need to find something between 4-5.5. 

Here is an article on the topic:

What is a Safe pH Level for Hair Care Products? eHow.com

Also The Natural Haven has a few educating post on ph levels too. 
Also visit Luv Naturals for great video series about this topic!!

This post is very general in a sense and I'm still learning.

Enjoy!