Once you build a fence it is inevitable that the weather is going to take its toll on it. Fence posts that were originally cut square allow rainwater to soak right into the wood resulting in expansion and splitting of the wood. We've found that by cutting the fence posts at a slight angle the water drains right off rather than sitting and soaking into the wood.
For a professional finish around trees planted in the lawn, loop a rope around the tree trunk and the shaft of a spade. Adjust the length so that the spade reaches to the drip line of the tree. Scribe the outline of a circle, then remove the rope and retrace the circle, sinking the spade vertically to make a neat, clean edge.