How to keep up the leather? Let's expand this to cover the entire interior:
1. Keep your car out of the sun.
2. Vacuum your car regularly. When vacuuming the seats, be sure to tilt them back so you can get all the dust and junk out from the seams.
3. Don't eat in your car.
4. Drink anything you want in your car -- as long it's water.
5. To dust your car, use distilled water and a microfiber cloth. Dash, instrument panel, seats, the works. Use the vacuum with a soft upholstery brush to get dush out of the air vents and texture the faux suede finish.
6. Windows: Windex, microfiber cloths and muscle.
7. If you keep your car out of the sun -- you won't have to treat the leather. If you do -- I'd go with Lexol as a bunch of other products look really, really, really greasy after application.
The underlying theme to all of this is: prevention.