From “Learning how to Learn from Masters: Module 3.3. Color in-depth”
This is a playful (and joyful) practice, but it is essential to spend some time doing this if you aren’t confident in your brushwork — I’d suggest a couple of twenty five minutes sessions as a minimum.
Take a large sheet of paper (the quality doesn’t matter — you will throw it away immediately anyway; what you are training are your arm movements). Hold your brush as far from the tip as possible, and as lightly as possible, allowing for a maximum flexibility of movement, so that you can use your whole arm (and, ideally, your whole body) while making your brushstrokes. It’s better to try this with several different brushes.
Work fast — don’t think. Your task is to make as many brushstrokes as possible in the allotted time slot, varying the direction of brush movement, the thickness of paint, the overall shape of brushstroke, and the pressure you apply. If the master you are studying has visibly characteristic brush strokes (like Van Gogh, for example), make more of these — but otherwise, aim for the maximum freedom of movement and variety.