Occasionally the mantle suffers from wear and tear and needs attention and because it's so in your face, blemishes like chipped paint or discoloration will stand out. If that's the case don't worry. It's a quick fix that any DIYer can do.
Here are a few tips on how to go about it:
Tools you'll need: sand paper, primer, good oil-based paint, a nice wide brush, drop cloths, rags. Possible necessities: paint scraper, wood putty, gloves, goggles, mouth protector.
Remove everything from the mantle
Remove anything obstructing your positioning around the mantle. This may include parts of the fireplace.
Wash down the mantle with a damp cloth and clean off any dust. Layer a piece of tape along the mantle/wall seam line and anywhere else along the mantle borders where it touches the fireplace.
No matter how good a painter you think you are accidents happen. Put a drop cloth on the floor around the mantle to protect the floor, whether it is carpet or hard wood, from dripping or spills.
Take some sand paper and try to remove the remaining paint or finish. You can also use a paint stripper or even paint remover. For paint remover you'll need to apply, let is sink in, and then try removing the paint. This may take several tries to get it right.
Let it dry and wipe down to remove any dust or excess residue.
Are there any cracks or holes? Fill them with wood putty.
Make sure the mantle is smooth and level.
Wipe down again.
Apply a primer. As always, it will enable the paint to stick better.
Allow to dry
Apply first coat of oil-based paint and let dry. When ready, apply a second coat, which will enhance the work you are doing.
When dry apply several coats of urethane to seal the shine.
In the end you'll have a great looking mantle.