Depends on the intensity of color you are looking for -- Starting with 50/50 and 25 percent dye/75 percent solvent and test to see how it looks on a piece of test wood. I use krylon spray on the test pieces to see how it will appear.
You can blend colors and add shades over other colors -- Air brush can also be used.
(The really permanent dyes are leather dyes or metalic dyes used with fibers -- Fieblings USMC Black is the blackest black with a finish)