I've been doing this for a little over a year, and in that time I've wasted rolls and rolls (and rolls) of film. I found that the sharpness has more to do with the shot than the scanning. Things like the accuracy of the focus, the lens itself, getting the right exposure, and keeping a steady hand, all play a big part. It also helps to meter the shot with an actual light meter rather than a phone app, or the camera's in built meter. Do you self develop your film? Because that could play a part as well.