It's easy to neglect your car's interior, especially when it comes to keeping the seats clean; however, keeping the leather seats in great condition can really make your car stand out. You'll want to remove surface dirt, clean the leather, and condition the seats regularly.
It's a good idea to vacuum the seats regularly. Use a vacuum hose and attachment or wet-dry vac to suck up any large particles of dirt. Take care that you don't scratch the leather. Remove surface dirt. If your seats are really dirty, you'll be able to see a layer of grime on the leather; however, even seemingly clean seats will have a layer of dirt and grime that's accumulated over time.
If you have perforated leather seats, avoid spraying any liquid onto the seats. Instead, spray a soft bristle brush and use it to scrub the leather. Then, wipe dry with a microfibre cloth. While you should lightly clean your seats every month or so, try to get your seats deep cleaned 3 to 4 times a year. You may want to do this more often if you have light-coloured leather or if you begin to notice grime building up.