I use Feibing's Pro dyes, usually thinned with 91% alcohol, almost always applied with an airbrush. Saddle soap to clean any hand oils, etc after tooling, and let dry overnight. Apply Feibing's leather care, and let dry overnight again. I've used Feibing's leather sheen, resolene, tan-kote, and occasionally neutral shoe polish as finishes. Leather shene and neutral shoe polish seem to be my favorites.
I've seen some leather that didn't dye evenly. I resorted to a wipe with 91% alcohol after the usual above treatment to get an even dye job.