Saphir leather creams and polishes are the global standard for quality. I've never found anything better, and I apply Saphir's Cordovan Cream to every single shell cordovan product as the final touch before it leaves the workshop.
I apply a thin, light coat with a soft cloth in a small swirling pattern, much like waxing a car. I wait about 10 minutes after applying, brush briskly with a thick horsehair brush (my favorite brush comes from Allen Edmonds), and then finish with a light buff using a soft flannel cloth.
Give it a try and you won't be disappointed.
Tip: Be careful with dark colored leather with light colored linen stitching. There may be some dye transfer to the thread. To avoid this, only use light pressure when applying the cream, and move to a different area of your cloth if you notice that it begins to take on more than just a little bit of the dye.