Hey, harvesting DOES give you A LOT of experience! And crafting too actually, you just need some higher level metals/logs...
You just have to find different types of trees. Click on a tree and u will see the name. When u'll reach lvl 9, you will get really nice amounts of exp, also from mining, you just need to seek these huge rocks. There are a lot of dark crystal/lava/elemental rocks on the islands North of the Swamp which is also North of Trinsic.
Also in Buccaneer's Den, there is like a hundred of black steel rocks which also give nice exp. And you need to be only level 6 to mine black steel rocks.
You will need a boat though, you can't use rune magic to teleport to any of the islands.
Moonglow is rich with birch for example...
Just travel around and you will find a lot of interesting stuff
Oh... and you will have to be in the battle projection of the world, when harvesting, unless your account is premium you can stay in peace projection(You can activate 1 week of premium account, by typing ".premium" in te game).
To switch projections, you will have to find a pentagramme in one of the big cities: Britain(Quintar), Vesper(Aiventis), Trinsic, Minoc, Yew(Rheos) or the Dark Dungeon of the Army of Darkness.