Fireplaces are lovely, especially when it is really cold outside. There is nothing more comforting or luxurious. However you cannot just let your fireplace sit. You must actively practice fireplace maintenance for the safety of your home.
Clean out the ashes regularly. Some wish to keep their fire lit at all times during the winter. You should let the fire die out at least once per day and let it go completely cold. Shovel out the ashes to help keep it clean and to prevent any complications.
The chimney should be looked at a few times per winter on the outside of your house and regularly inside. Check all the masonry for any cracks inside and try to look for any escaping smoke. Look for things built up on the outside of your chimney, like ice or nests. Clear them away and have a professional repair any brick work.
Know what temperature your fire needs to burn at for everything to be safe. Some people like to avoid high temperatures, thinking it prevents fires. It really just builds up creosote when you burn your fireplace too cold. Burning too hot does, indeed, cause chimney fires.
Your liners should be replaced often. Know how old they are. Chimney sweeps are really the best people to ask about this. Ask your chimney sweep if you need certain types of cleaning logs to clear out your chimney.
Keep your fireplace area clean. The cleaner it is, the easier it will be for you to tell if there is damage. Polish any metal and keep the bricks clean with special brick cleansers. In this way you can see easily if there are any flaws or cracks. Do not clean with a vacuum, since there may be coals still hot, even after a long period of time. Make sure there is nothing flammable by the fire--even a rug.