From Cook's Illustrated:
For a better baked potato recipe, we found that traditional slow baking is best. This is mainly because of the effect it has on the skin; the skin of a potato baked at 350 degrees for an hour and 15 minutes simply has no peer. The most important step to a fluffy potato was opening it wide when it was hot to let the steam escape to the air rather than getting trapped in the potato, which would make it soggy.
Heat oven to 350 degrees. Scrub potatoes well to remove dirt. Place on middle rack of oven, and bake 75 minutes. Remove from oven and pierce with fork to create dotted "X." Press in at ends of potato to push flesh up and out.