How many of these are you getting wrong?
1. Don't store it in the bathroom.
Keeping fragrance in the bathroom might look pretty in a tray on your sink, but it might be time to invest in a dresser, because the heat and steam coming from your shower in your bathroom causes a lot of humidity and that isn't a great environment for a natural fragrance.
2. Keep it in a cool place away from sunlight.
So, not on a windowsill. Move them to a place away from UV exposure (unless of course you're taking an insta pic, a short time is perfectly fine and makes for a great shot!) so the UV light doesn't get to the fragrance.
3. Try not to leave the top off for too long.
Put the lid back on. The longer you expose the perfume to air, the quicker it oxidises which can affect its longevity.