Soak, don't soak. Salt, don't salt. There are as many rules about cooking beans as there are types of beans. Here are rules for the rules.
Soaking: Most cookery writers insist on it, though a new school dismisses the practice as witchcraft. In fact, the usefulness of it is dictated by the variety, age and size of the bean. Dried beans are soaked to rehydrate them to the point of peak freshness, before they began to dry on the vine. With older, drier, or larger beans, soaking can significantly cut down on cooking time. For small, recently harvested dried beans, it can be foregone.
Boiling: Bringing beans to a boil at the beginning of cooking is important to cook certain proteins, but keeping them at a boil will split and toughen the skins. After they reach a boil, heat should be reduced and the beans cooked at a slow burble.
Salting: Conventional wisdom dictates that dried beans should only be salted toward the end of cooking, because the salt draws moisture from the bean, producing an unpleasantly dry texture. But exhaustive tests done by Times columnist Russ Parsons showed that beans cooked with a teaspoon of salt per pound compared to beans cooked without salt cooked to exactly the same degree of softness in almost exactly the same time. Moreover, the beans salted during cooking required half as much salt.
Digestibility: The best way to ensure that a bean dish is easily digestible is to cook it thoroughly. Undercooked beans will cause indigestion. Properly cooked ones shouldn't. However, products such as Beano introduce an enzyme that helps break down stubborn starches and sugars in the beans.