Stir the paint after adding a little thinner, then lift the stir stick up out of the paint, the paint will run off the end as soon as you lift it up and as the paint runs off the stir stick it will be in a solid stream but after a couple of seconds or so it will go from a stream to drips, I add thinner until the time it goes from a stream to drip is me counting from 1 to 6 or 8.
Hope that helps.