This is probably the easiest thing in the world to cook, but surprisingly few people know how to do it right. The most common mistake people make is wrapping the potato in foil, which makes the skin stay soft and yuck. The second most common mistake is to not scrub the potato, which makes the skin double yuck.
Preheat the oven to 400. If you like the skin extra crispy or are cooking extra big potatoes, turn the oven up to 425.
Pick out however many potatoes you want to cook. It is best for them to all be roughly the same size so that they cook at the same rate. I prefer 2 or 3 small potatoes to 1 big potato because the have more surface area and, therefore, more skin. (The skin is the best part if you cook the potato right. If you think you don't like the skin, then you haven't tried a correctly baked potato.)
Scrub the potatoes with a stiff-bristled brush, like a dish washing brush. Don't use soap; just scrub under running water. Each potato takes maybe 15 seconds to scrub. The reason you are scrubbing is to get all the dirt off the skin. (They grow underground, you know.) Scrubbing will make the skin lighter colored and smoother. Sometimes it has a faint green color.
Pat the potatoes dry with a towel and stick each one a couple of times with a fork.
Coat the potatoes with butter or olive oil. I use PAM butter flavor cooking spray. (It's quick, easy, and tastes great!) Sprinkle with salt or seasoning, like Cajun or Greek seasoning.
Put the potatoes directly on the top oven rack and bake for an hour. Particularly big potatoes should cook for an hour and 15 minutes.
That's all there is to it! Take 'em out, pet each in a bowl with shredded cheese, butter, bacon bits, chives, salt & pepper, sour cream, and whatever else you like to put on baked potatoes.