Now draw fingers schematically, walk an eraser on lines that they were hardly visible and only then trace the correct shape of a hand and a brush.
Draw the lines on a hand indicating performance of muscles and ledges after that again walk an eraser that it was badly visible to the line.
2H and HB put with a pencil shading, having allocated highlights.
2B and 4B we put with a pencil cross shading, creating dark sites.
Apply shading after that compare to you drawing to mine on a brush, correct defects.