My method is rather inexact but it could be modified to be very exact if you wanted to use a scale.
I think most clay would tint the same way. Mixing color into any clay will change its color. You could do this in a number of ways.
1. Add clay that has another color
2. Add color directly
The first is self explanatory, but the second might not be. If you were tinting polymer clay, there would be things that wouldn’t work so well with it. For instance water paint added directly might not work as well as ink. This is to say that it wouldn’t be absorbed into the clay, and would always bleed out a little bit onto the person to touched it next unless sealed.
My air dry clay, and I am going to assume any air dry clay, can take practically anything to color it. So, inks, acrylic paints, oil paints (though oil paint might start breaking down the structure of the glue) water color paint, other clay etc etc. This is subject to a lot of experimentation.
Adding Acrylic Paint: When you add acrylic paint to your air dry clay, while the clay is wet it makes the clay sort of gummy. The reason for this is because it has a wet texture of its own. So when you knead it in, the stuff will instantly start sticking to your fingers. To combat this I stuck my fingers in starch (potato, corn, rice, whatever you have in the house) and continued kneading. If ever your clay becomes too gummy you can do that as many times as needed. Be aware that this will stiffen your clay, but also make it more prone to cracking even before it is dry. You will have to shape this clay very fast and set it into place. All in all though – Kneading acrylic paint into air dry clay is very fun, and kids would love it because its sloppy goopy and very satisfying.
Also I think that a worthy experiment would be to crush up some of the dried acrylic paint I have and add it to the clay. This would take more time to knead into the clay and if you didn’t work on it long enough you would have lumps… but if you crushed it up fine you would have a nicer consistency. Micah powders, sparkles etc could also be a lot of fun.