Does anyone know how to stop this issue:

I've had my 2001 X5 for about 1.5 years, and a few months after I got it, one of my signal bulbs said it was out. I replaced it, noticing that it didn't look blown, and it was fine for a while. This has continued to happen on and off with different locations. Even with the front turn signal. I've replaced all bulbs and "bulb holders" in the rear, and the driver's-side front signal once. Again, I've got the front driver's signal acting up again, and one of the brake lights. It seems like I can't go more than about 3 or 4 weeks before a bulb reports being out. Is there something I should prep the bulbs and sockets with (like di-electric grease) to keep this from happening? has anyone else had this kind of trouble?

Thanks,
Andy E.
Sarasota, FL
2001 X5 4.4