Like wood, leather can also be damaged by excessive heat, extreme changes in temperature, or direct sunlight.
Use a vacuum on upholstery to remove any imperfections, crumbs, dust, etc. These specks act as an abrasive which can tarnish the integrity of the fabric. Don’t forget to clean under cushions, and other hard to reach areas.
To maintain the fluff, and shape of the cushions - flip them regularly to avoid overuse on one particular side, or switch them around from right to left. Also, over the course of a year, experiment with the upholstered seats in different areas along the floor plan. This will vary the use, and help preserve the leather. You can also protect the arms of a couch, or the seat cushions using arm caps or a plastic/matching slipcover.
If the leather is coated, certain cleaning agents like creams or conditioners are available to restore the original shine. Follow the product guidelines. If the leather is uncoated, routine dusting is preferred instead of using chemicals, to preserve the strength of the original color.