Ditto what Torstan said - if you think of a bunch of these cartographers as Masters, remember that a Master also needs Apprentices (well, minions too, but I won't go there...). Only, see, you're now IN the Guild, and all the secrets of mapmaking are available, if you can just slave away for seven years.... no, wait, my analogy is breaking down. How 'bout "plenty of these Really Masterful Mappers' Mysterious Methods are right there in the tutorials and in-thread help". Grab a likely tutorial and dive in!