Before I dyed my first holster I tried different dye ideas on scrap leather to see if I would like the results. I currently apply olive oil to my holsters and allow them to sit out in the sun to tan. I have gotten some good results doing this. The more oil you put on the holster the darker it will be. I seal my holsters with a 50/50 mix of water and mop and glow, followed up by polishing with Kiwi neutral shoe polish. If you do a search for holster finishes you will find several good ideas on how to protect your work. Experiment and see what works best for you.