For the smaller cuts that dont go through, you should still have an outline of where it should have cut, use a small hobby knife to get the edges and corners. Also if it is a 90 degree corner that doesnt quite get the corner, when you set the plotter, make it go past the intersection point by a few mm with each line.
I can go on for a while with tips, I worked in a vinyl shop for a while a few years ago, any specific questions feel free to let me know.
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