štedeti

1. (of money) to save
   Već godinu dana štedim za novi auto. — I've been saving for a new car for a year.
2. to economize; to save on
   Moramo da štedimo struju zimi. — We have to save electricity in winter.
   Ne štedi na dobroj hrani. — Don't skimp on good food.
3. to spare
   Nemoj me štedeti, reci mi istinu. — Don't spare me, tell me the truth.
   Na poslu uopšte ne štedi sebe. — He doesn't spare himself at all at work.

What you save on takes na + loc.: štedeti na grejanju; the perfective is uštedeti for saving and poštedeti for sparing.