Most fireplaces are made of solid steel, iron, or masonry, requiring few fixes. If your fireplace has glass windows, a periodic cleaning with vinegar and a stiff brush will keep them clean. There are some fireplace fixes you can do in just an hour or two once a year. The most practical one is cleaning the chimney.
A straight chimney with a clean-out door at the bottom is relatively easy to clean. Before starting any chimney cleaning job, however, make sure the fireplace doors are fully closed and sealed or, if it's an open fireplace, that it is covered with cloth or cardboard and sealed. You don't want soot in your home.
Chimney cleaning brushes are available at many hardware stores and building material retailers. If you purchase a set, make sure they are the correct size for your chimney. You also can construct your own chimney cleaner by weighting a burlap bag with old rags, sawdust, or some other waste material and lowering it into the chimney from the top. Raise and lower the bag several times and the soot will dislodge from the sides and fall to the bottom of the chimney where it can be removed with a small shovel.
To test the chimney for possible leaks, start a fire in the fireplace and, when it is burning well, throw in some material that will cause smoke. When the smoke begins to billow from the top of the chimney, cover it with a piece of heavy, wet cloth for a short time. This will force the smoke to find some other exit from the chimney, if one exists. Mark any leaks with a piece of chalk and repair them later with a chimney patch product available at larger hardware stores.