Hey Folks!
I have found that the best method for mixing is to use small syringes. Available at almost any drug store, (explain that they are for paint mixing and not drug use, it may help in obtaining them!) they will give you an accurate ratio mix (eg:2 to 1 = 20ml + 10ml) simple math.
As to mixing, break down and buy a paint mixer, Badger has one for $11.20 available at www.scaleracecars.com.
On to cleaning. If you are using acrylics, use an empty margarine container half full of water, and run the mixer in that for a few seconds, remove, & dry. If you are using enamels, use a small glass jar with the appropriate amount of thinner in it, run mixer in it 'till clean and then rinse clean. It might help to hold a piece of paper towel over the top of your container of choice to avoid splashing.
I hope that this info is of use to you, all the best, John.