Handle your leather bag with clean hands - oil and residue will easily transfer to leather. Once or twice a year, remove dirt buildup by wiping 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. To prevent drying out, massage a high-quality leather conditioner into the leather and use a clean cloth to gently wipe off excess about once per year.
If you're leather item gets wet, gently blot (not rub!) excess as soon as possible, and allow the rest to air dry. Do not use a heat source to speed up the drying. When drying a bag, stuff the inside with newspaper to help the bag hold its shape and to help absorb moisture from the interior.

Proper storage is important when caring for leather. Store leather in a space away from heat, humidity, sunlight, and dust - preferably in a fabric (not plastic!) bag and/or box.