fletching is best done by going to the city of Heartwood, which is accessible through a gate in the middle of Yew.
Go to the bowcrafters. The Bowcrafters offer 4 quests that are bow related....
One asks for Bows (a simple bow)
One asks for Crossbows (Ingenious Archery I)
One Asks for Heavy Crossbows (Ingenious Archery II)
One asks for Repeating Crossbows. (Ingenious Archery III)
See which of these items is the hardest one you can make successfully, and do its quest over and over.
(to get a different quest without accepting ones you don't want, pull a status bar off the NPC and fast-click it repeatedly until the quest name you want comes up, then accept it)
Remember to have your wood in the top level of your pack and have "Mark as quest item" turned on in the crafting menu. Make only the number you need for the quest, turn in, and get a new copy of the quest before making stuff again. When your pack fills up, get any runics from the reward bags, then discard the rest.
Also remember to take as much wood as you can down there. Say, 300-400 wood on you, and 5 pack horses/llamas loaded with 1600 each.
Carpentry, on the other hand, is a pain, as there really isn't much you can do to get rid of stuff you make other than throw it away. There are some things you can make to turn in in Heartwood, Britain Library, etc. but there's not 100% coverage of the skill from 30 to GM with quests like Fletching has.