Tips for Cutting
Never assume your angles are perfectly 90 degrees. Mark them before cutting.
For outside corners, I cut about 1/16 longer than the measurement. It just works better that way for me.
If you have trouble holding the trim against the fence, cut a scrap piece of wood in a triangle that is the size of your gap.
Generally speaking, I don't do the "cut the leading edge" trick. I usually cut the inside corners first (one at 45 and then mark the opposite piece for the leftover angle), then work outward from that corner.