Each of the 4 continents has two special locations marked by a sign post. You should visit these places to raise your attributes or fulfill a quest. You can get the reward again and again, as long as you don't visit one twice in a row. One sign post is special, because it provides you with weapons. So make use of it and grab the best weapons from here and sell the inferior weapons (which you must own to get the better ones) afterwards. You must get a ship before you can reach them though. The sign posts are also the places you have to find for the kings. Return after you fulfilled your quest and the kings will raise your "Strength" (there is no sign post which raises this attribute).