A good habit to get into is to bring your hands together a little bit when you are hitting the yoyo into the top string, this allows the yoyo to push up the top string and go over you pointer landing in a nice one and a half mount.
another method for getting into the mount is to throw a trapeze then take you throw hand pointer put it into the loop that is formed and pull you hands apart, this movement pops the yoyo into the one and a half mount as well.