Prep/Condition your leather with a Over-the-counter leather cleaner/conditioner.
Just a short trip to your local advance auto and you got a good solution to your problem (walmart is highly recommended as I know that they have both Mothers products and it's usually a lil cheaper there).
1.) Mothers VLR complete interior cleaner/detailer (vynil, leather, rubber).
2.) Mothers Leather cleaner/conditioner (leather care).
Try that for now and then move up to the professional mail order stuff. Anything from Detailers Domain is Great. Someone did a article about a year ago on here reviewing the Swissvax leather care treatment.
1988 325i sedan (Cirrus Blue Metallic, Silver Grey Leather)
2011 128i convertible (Blue Water Metallic, Grey Leather)