There are many "recipes" out there for the paste and everyone that does this has their favorite. Rather than cooking my own paste I buy Elmer's Art Paste from Dick Blick. It is cheap, makes a lot, it keeps forever and it is handy to have around in it's little box just waiting to be mixed with water. After the paste of choice is made I add acrylic paint. You don't have to use the good stuff to get great color. The mix is approximately 40% paint and 60% paste. There is no need to measure, just add paint until the paste has the opacity that you'd like.
The mosaics in the previous post were made with paste paper scraps. (I always have lots of those around!) These pictures are bigger sheets. Can you guess what tool was used to achieve the effects on the orange one?
PS. It's a sponge mop!