A fireplace mantel is either a main focal point of the room or a large secondary focal point. Either way it is a great location for decorative touches that will show your personality and style. There are a few tips to know regardless of your style or preference.
Tip #1: Start with the foundation piece
This is typically the largest piece that sits tallest over the fireplace
This needs to be an object that is balanced with the fireplace box
Tip #2: Flanking Weight
These are the objects to the right and left of the foundation piece. These objects do not need to match (pending your style) and they do not need to be the exact same size, height, etc
These pieces should balance each other out visually
Tip #3: Additional items
Not all styles will call for additional items, but if so… Begin filling in the middle beneath your foundation
These items should be smaller than the flanking weight and should not compete with the fireplace box
Tip #4: These items should create a visual triangle above your mantel
All pieces on your mantel should be spread across the entire mantel with a peak in the middle. This does not need to be an exact triangle, but the overall concept.
Tip #5: Portion and Scale
Keep in mind the height, size, weight and proportionate value of each piece and how they relate not only to each other, but the fireplace, fireplace mantel, ceiling height, woodworking, and the rest of the space
Pending your style, you may want to opt out of various tips. The goal is to remember balance, visual weight and overall cohesiveness of your mantel and the space around it. This is a great place to show your personality, interests, family heirlooms, favorite décor, etc.
Remember that anything added to the hearth space of the fireplace should be played as an additional piece of the fireplace mantel.