Most balls on greens stop because of the angle of descent , not due to spin . Spin has an effect to be sure , but it's a secondary factor to the angle of descent . That being said , one of the most effective ways to get the ball to "bite" more quickly is to ensure that you are not delofting the club too much at the point of impact .
To guard against this , try moving the ball slightly ahead in your stance . You still want to have the feel of a descending blow , but not quite as much as a normal shot . Then make sure you swing thru to a full , high finish . Think of more of an "arms"-finish rather than a body finish . This assures that you maximize the loft used in the shot . -- K.