The most important things to remember about leather is not to get it soiled, soaked, or let it dry out. So don't dirty it, wet it or leave it in the sun.
The most common mistake people make when taking care of leather is using too much conditioner. Leather comes with surfactants (protection) from the tannery. EBB & FLOW products are all very well protected when new. If you apply too much leather chemicals or you apply them too often, you may strip off the protection the tannery applied.
To keep your piece soft, supple and preserve the matte finish, wipe it down with a damp cloth whenever you think it needs freshening up. Wiping the leather with a damp cloth will pick up any loose dirt particles on the surface.
If you find a scuff mark is just on the surface and you need a quicker solution, you can try simply using some clear shoe polish. If you are feeling fancy, creams, oils, beeswax (that you rub into the wallet with a clean, dry, soft white cloth) are great for conditioning and waterproofing soft leather.