@Mame,
Stepping in, to answer what I think Ypir means.
I'll agree that I have had trouble figuring out his or her posts - and wish he or she would buy a book on art techniques, or better, take a class.
Anyway, I'm an oil painter and I do starter sketching on a primed canvas with a dilute wash, moving the brush around easily and not trying to be perfect in any way - it is just a matter of "breaking the white", or whatever color your primer is. Later I may add washes to show general color areas. That is all just a start, giving me a sketch to play with or play against. My canvasses are usually fairly large so the starter sketch probably involves my moving my whole arm, or lower part of my arm, not just my fingers gripping a brush. But this can be done with smaller canvasses, with the lower arm and wrist.
This is only one way to begin a painting, but a way I use myself.