After making several minimates with skirts or dresses, I made a pattern for myself to follow. Without the pattern, it would take me several tries to get the angle and size just right for folding around the minimate body. It occured to me that other people might benefit from this pattern, so I created a sheet with these two patterns, as well as a few others. Simply print this sheet on plain white paper, and put it underneath a sheet of thick plastic, such as minimate packaging. Use a sharpie to trace the outlines, cut it out with a hobby knife or scissors, and then fold it at the lines. Some of the items have additional instructions.
I tested all of these items on actual minimates, and they worked great for me. I used the dress pattern for my recent Zelda figure:
This template can be found in the Downloads section at the top menu. I renamed the previous downloads section to Decals in order to keep everything organized. There is also an Illustrator file if you would like to modify these patterns in any way. I hope this is a useful tool for you!