Be sure you’re cleaning your leather bag with clean hands. Leather bags are susceptible to absorbing grease and oil.
Do a quick cleaning every other day, with a soft, dry, or slightly damp cloth. (Do not use too much water; leather takes time to dry.)
Once or twice a year, do a more thorough cleaning to remove dirt buildup. Wipe down your leather bag with a cleaner made specifically for leather. Apply in a circular motion, and wipe off with a slightly damp cloth to avoid clogging the pores of the leather.