Vacuum your leather sofa regularly with a soft brush attachment to remove dust and dirt. Use a damp rag to wipe off any excess dirt and snag any crumbs or hair between and under the cushions. You can use a mild soap on the rag if you wish, but make sure to remove all soap residue with a clean, dry towel.
Apply a leather conditioner after the water dries. Most furniture stores sell leather conditioner made specifically for sofas and other furniture. You can also purchase leather conditioners at most superstores and department stores. When using a new conditioner for the first time, test it on a small, inconspicuous area. Even though these conditioners are made for leather, some of them can alter color and texture slightly.
Refrain from using other commercial furniture cleaners on your sofa unless they are made specifically for leather furniture. Most stains will clean up with just a damp rag. Make sure to wring excess water out of the rag before using it on your sofa. Too much water can stain the leather. Talcum powder and cornstarch can help break up grease on leather. Let the powder or cornstarch sit on the stained spot for about four hours and then gently wipe it away with a clean, damp cloth. If you catch ink stains quickly, moisten the spot with hairspray and wipe it away. This may not work on older ink stains. Always test the hairspray on an unnoticeable part of your sofa before using it as a stain remover.
Keep your leather sofa out of direct sunlight as much as possible. Sunlight can fade leather over time. Keep sharp objects away from leather to avoid punctures and tears. Smoke and cooking fumes can penetrate a leather sofa and cause lingering odors and fading, so keep your leather sofa away from these pollutants if possible.
Small scratches usually fade over time. Commercial leather dyes can help cover deeper scratches that are more noticeable. Most furniture stores also sell touch-up kits that match the color of your furniture for minor cover-ups.