I have 2 lightbulbs in my house that no longer work, but I can't get them out of the sockets to replace them. On one, the glass is already broken and it's just the metal screw part that's still in the socket. The other one is still a whole bulb stuck in there. Any suggestions as to how to get them safely out and how to keep this from happening again?

Turn off the electricity to it, and use a needle nosed plier to unscrew it. Another option is to wad up a washcloth or other piece of material and cram it up in there and turn it.

To help prevent this in the future, you can give the screw part of the bulb a shot of WD-40 before screwing it into the socket.

So should I just tug on the bulb that isn't broken and not worry if it breaks? That's great that I can use WD-40 -- I thought that would interfere with the conduction or something.

For the bulb not broken, wrap it with a THICK cloth, in case it breaks, and try unscrewing it.

If it does break, then use the pliers to remove it.

Don't forget to turn off the electricity to it, though! ;)

I've heard of using half of a potato for broken lightbulbs... same principle, and the bonus that it will hold any pieces of glass safely.

For the unbroken one, you can probably do it with a bit of extra force. Wear a heavy work glove, and probably some eye protection, just in case. You may also be able to use what I've taken to calling fake pliers: Use a belt or something similar (anything rubber or leather will work pretty well) and wrap it once around the widest part of the bulb, grip the two ends together with as much force as you feel comfortable applying, and turn it like it's the handle of a pair of pliers.

Definitely use WD-40 or something similar. Wait long enough for it to dry thoroughly before putting a new bulb in or re-energizing the socket. It won't take long, but always better safe than sorry where electrical things are concerned.

Try prying the outer shell away from the socket, and then griping it with pliers. If you used WD-40, and have a new bulb in the socket, again shut the power off remove the bulb and carefully clean it and socket. I think WD-40 is a bad idea. It may help free something, but in the long term, it creates more problems than it solves. It tends to leave a gummy residue if not frequently reapplied. The heat of the light bulb could bake it solid cementing the bulb in leaving an even bigger problem next time. For a spray lube, I always use a silicone. They are much more stable and never gum up.

If this is a reoccurring problem, I would pickup a tube of dielectric grease at an auto parts store, and put a light coat on the bulb base. It is formulated to be stable in a hot environment and allow the spark plug boot to be removed years later.

You might consider a compact fluorescent. It would be a long time between replacements and you would have a substantial ceramic base to grip.

Just an added fyi on the wd-40 issue: This is an oft recommended tip by electricians and diy books and websites:
light bulb wd-40 - Google Search

I manage 400 apartments and our maintenance staff started wd-40ing the bulbs 5-6 years ago and we've 1. never run into any problems as a result of it, and 2. have far less stuck or broken bulbs to deal with since then.

Thank you! With gloves, goggles, pliers and a rubber strap-type jar opener, I got both bulbs out without any broken glass and the WD-40 made the new ones slide in very smoothly.