The finish and decorative fittings on the outside of the instrument are there to protect the body and to look good. Day-to-day care is mainly gentle cleaning.
A dry wipe with a clean soft cloth is enough. Solvent-based cleaners, abrasive cloths and stiff brushes can all damage the finish and leave marks that are hard to put right.
When moving or transporting the instrument, take care around any fittings that stand proud of the surface. These points take the force of a knock, and the finish is likely to chip or crack there.
Also keep an eye on the joint between soundboard and body, and on the seams where fittings meet the frame. Long exposure to damp, or uneven stress, can work these seams loose.
If a large area of finish is damaged, it is better to hand the instrument to a professional repairer. Matching colour and texture by hand is difficult to do convincingly.