Cleaning with a very mild soap solution is an ok way to go, but if you get the soap solution strong enough to do any cleaning you are stipping essential oils from the leather. If you choose this path, be sure to condition when you are done.
For modern automotive leather-regardless of color, you should use a pH-balanced cleaner followed by a conditioner. There are several brands available. A few that come to mind are Lexol, Leatherique and Leather+Aid.
If you don't like shiny, stay away from conditioners with waxes in them. In addition to adding gloss, they tend to clog pores which will eventually block conditioners from absorbing.