Beets can be a somewhat vexing vegetable to tackle if you are unfamiliar with them. They have a fairly sweet flavor that takes ownership of most dishes in which they are incorporated, and the ruby red color will infiltrate anything that you add them to (and do a number on skin and clothing, as well). I find that the easiest way to cook them also results in the tastiest results, so I roast them whole. Less work, less mess, delicious end product.
When selecting beets, try to get a group that are uniform in size, which will simplify the cooking process even further. A larger beet will take longer to cook then a smaller one; it's as simple as that. Choose beets that have fresh, vibrant leaves still attached and that are heavy and very firm.
Get the beets home and cut off the stems very close to the beets themselves. I save the greens to put into soups and other dishes. Wash the beets thoroughly, place them whole in an oven safe dish, and bake for about an hour at 375F. Pull them out and let them cool down enough to peel, then slice and serve them. Roasting the beets intensifies the flavor, as opposed to boiling them. Cooked beets are also easier to peel and much, much easier to slice We like them as a hot side dish to roasted chicken, or served cold the next day for lunch with egg salad (or some of that leftover chicken).