When I said simple, I meant it. To farm trees early game, simply collect around 9 saplings (I recommend Oak, since it is nice to build with and drops Apples, but any tree will do), and plant them in a 3x3 grid somewhere near your base. As time goes on, your saplings will grow, and you can use Ore Excavate to collect large amounts of wood at a time, since the trees will all be connected. After you break the trees, the leaves will automatically decay. Simply make sure to replant your saplings, and feel free to continue making the sapling square bigger and bigger, in order to increase your wood gain, just be sure to have some food to replenish your hunger after using Ore Excavate. Stone tools are great for this, since you can repair them very cheaply and easily with Stone Sharpening kits, which can be created in the Part Builder.