Many beets are sold in bunches with the tops still attached, while others are sold with the tops removed. Look for beets that are firm, round, with a slender tap root (the large main root), a rich, color, and smooth over most of the surface. If beets are bunched, you can judge their freshness fairly accurately by the condition of the tops. Badly wilted or decayed tops indicate a lack of freshness, but the roots may be satisfactory if they are firm.
Avoid elongated beets with round, scaly areas around the top surface — these will be tough, fibrous, and strong-flavored. Also avoid wilted, flabby beets — they have been exposed to the air too long.
As the beet greens are very nutritious, cook them as you would fresh spinach leaves.