How to spot a great piece. First, follow your heart. This is something you will be living with and using daily, not putting on display in a museum, so think of your own needs and style preferences first — and consider any investment value a bonus.
Then take a closer look at the piece: Is it well constructed? Does it look like it's been well cared for? Note any wobbly legs, broken pieces, cracks, stains etc. Also be sure to ask the seller about the history of the piece.