I originally got this technique from someone who got it out of the new Somerset Workshop mag/book. I changed it to how I do things. Here is the post that explains the process:
Here is another example of it:
Here was my original experiment - it has morphed a lot since then:
I have in the posts where I got the emulsion/house paints and what brand it is. I think that one of the posts even tells you which colors I used. You can also buy a big can of white latex paint and add acrylic to it to color it. The key for me is the instant coffee. I let it pool and then dry completely before doing the latex/acrylic paints. The instant coffee will remain kinda glossy when dry. The coffee stays a little tacky. It actually helps me to pull the latex paint off certain areas so the coffee areas are more exposed. The tacky part sticks to the paper towel when I am dabbing.
Hope that answers your questions.