I asked a similar question, however if was for my seats.
"Regarding leather, I use Furniture Clinic Ultra-Clean, and then follow that up with their Protection Cream. You should only really need to do your leather twice a year using this stuff. Whenever you feel like cleaning your car (in my case, once a week or fortnight), you can simply wipe your leather down with a damp microfibre cloth, and it should come clean without the need for extensive deep cleaning using leather cleaner etc."