I used to make natural deodorant that I sold. I would use 1/4 c of coconut oil, a little grapeseed oil (maybe 1/4 tsp), and 1 Tbs of baking soda. To that I'd add boric acid (a small pinch) to prevent bacteria build up, and some essential oil to scent. Any of the citrus oils will cause irritation, so try to stay away from those. One of the best ways to prevent bacterial growth is simply to rinse your hands well and dry them with a clean cloth. I always advised my customers to do this when using either the deodorant or body butter I made and had not one complaint of spoilage.
Hope this helped !
"You can always do more than you think you can !" Sensei Scash