I have a couple of light bulbs that keep burning out. They are in my garage (attached to house). Sometimes they last a month, sometimes just a couple of days.
Answer:
Make sure there is no power to that circuit and then remove the bulb. Now reach down into the fixture and lift the little copper tongue 1/8". A bit of fine sand paper on the end of a pencil will clean the contact surface of the tongue and then you're ready to put in the bulb again. You can now turn power back tothat circuit. This will make bulbs last much longer unless there is a supply problem.