First holster ? That is a nice holster for a first, I wish mine looked as good when I made my first holster ! Recomendations, well first you look fine in the trigger guard area for a OWB holster as long as the trigger is covered but would extend it for a OWB holster as that is one of the points used for securing weapon. I would make a pocket for your clip and rivet it to the leather or use a chicago screw, this will secure the clip and keep it from moving too much. Donot use shoe polish as the finish will rubb off on your chlothes, not a good thing. I would buy some leather dye and acrylic resolene for a finish. The stitcheing looks good for what you used but I think next time I'd use some wax nylon thread and maybe a stitching needle, I don't think they'd break as often as sewing needles. Your design is clean but I'd stay away from the sharp corners and use mor of a curve as finishing the edges would be easier. All in all a very nice job. I can't or I'm too ashamed to say how many holsters went into the scrap pile until I finished one that was "good enough " so to speak. I can't speak for the other holster makers out there but I am my own worst critic. Keep up the good work, you are well on your way.
Best,
Rhome