Understanding "פסיק רישא דלא ניחא ליה" (inevitable results from one's permissible action whereby one receives no benefit from).
Putting Away Laundry That Is Still Hanging Around From Before Shabbos. Taking Out Frozen Milk or Frozen Challah for After Shabbos;
Is one allowed to wash for challah if on their hands are printed numbers, pictures, letters.
Understanding the concept of "הפסד" (paying for losses).