If you are playing natural skin drums it is best to detune the heads after playing. When you go to play your drums again, you can tune them back up to pitch. This will preserve the heads longer from temperature and humidity.
Some players say to not put oil on your heads, but if they do seem to be drying out, add a small amount of oil on the heads surface. This only needs to be done a few times each year if at all. The natural oils from your hands will help maintain your heads.