Goodness knows I am no expert
QuelleFromage, but from what I've gleaned, you can just rub any marks with your fingers a bit and carry on. It seems the oil from your hands/fingers is enough to massage the mark and begin the blending/patina-ing process. It's my understanding that you don't really want to go with any products other than a bit of saddle baume once in a very long while if the leather seems a bit dry. There are opposing views as to whether that's a procedure best left to the craftsmen or whether a reasonably competent person could tackle it themselves if needed.
My sense is that there's not much help for the somewhat 'ugly duckling' phase where there are lots of scratches etc on otherwise smooth leather; you need to just let the natural process of developing the patina do its work. The more you wear it and expose it to the elements, the faster you get to the the glory of well-aged barenia. As my bags are pre-loved, I can only dream of following my own advice