Though my style tends to lean towards a more eclectic aesthetic, I find rooting rooms with traditional furniture is a good rule to avoid crossing the fine line into a cluttered space.
For more inspiration
Pairing a classic piece such as the Howard Armchair with directional accents is my tried-and-true solution. The addition of Kelly Behun's equal parts whimsical-and-considered footed bowl for L'Objet or a few well-placed dynamic patterns creates a subtle contrast that I rather enjoy. It's an alchemy full of depth and interest which is imperative for good design.