Leather conditioner prevents cracking and dryness of your bag. Rub a it into the outside of your bag using a clean cloth. Once a month, apply leather conditioner.
To establish a barrier between your bag and the elements, dab a beeswax cream into the outside of your leather or use a leather spray protectant.
Once a month, or whenever it becomes obviously dirty, use a suede brush to brush away dirt and grime on the outside of your suede bag.