Its one of the easiest skills to level actually.
Collection goes up every time you time you click an item pool that contains; Grass, Clay, or Water
Cutting is Woods
and Mining is Ores, Rocks, Jades, and Gems
I have not checked into what skill affects Crude Oil or Mercury but I would but its mining.
Scorpio 2
Felixoo7
http://wlodb.com/topics/2116 <-- Fishing!!!
http://wlodb.com/topics/2325 <-- Monsters!!
http://wlodb.com/topics/3690 <-- Economy!!!