I have covered the bottom first then come over the top with a different color but before I iron the area where they over lap I have tacked on a piece of balsa sheeting onto the fuse just over the bottom color, bring the top covering over the top of the wood then used a straight edge where I want the seam and cut with a sharp knife. Remove the wood sheet and iron down. Then like Don I use the line tape. I now have a covering stripe cutter and use covering instead of the tape. This is just one way I have done it, over lay and cut. I have also made up paper templates and pre cut the covering but it doesn't always work out well.