You don't need to look at the ball to stop heading changes. As others have written, look outside at an aim point. Preferably as far away as you can see eg something on the horizon. Keep the wings level while using your feet to keep a convenient speck on the windscreen aligned with the aim point.
If you need to adjust heading to return to the aim point (or turn to a new aim point) then use a gentle, co-ordinated turn to get to the new aim point. Once there, return to using your feet to *prevent* an unwanted heading change.