Daph
Put up the corner boards first. If the siding boards are long enough to go from one end to the other..then cut them an 1/8" long, put the ends up against the corner boards and "bow" out the middle to make it fit. Nail it from one end to the other and that little bow will push the ends hard against the corners. The reason I say tight on the corners is because when you paint you can just fill the gaps full of caulk and paint over them....but when you stain you dont want to see too much caulk, which means very little room for error.
If they are not long enough to do one piece all the way across, then you should put a slight miter on the pieces that go together to make the run across as this will make the joint much less noticeable. Your DH probably knows what I mean![]()
We are actually planning on hanging the boards vertically. Sort of a board and batten design. At least that's what we PLAN.