I'd recommend Meguiar's D101 all-purpose cleaner diluted at about a 10:1 ratio. Spray on lightly, agitate, wipe off with a microfiber. It's cheap and it works. I use it for car stuff and other things around the house. It's also safe on leather. For a deeper clean, agitate with a brush before wiping off to lift off embedded dirt.
Folex would also work very well, with the same technique, but will cost more.