One thing I have always loved about costuming and cosplay is trying to make the drawing or idea in to a real item. This involves a lot of work and using items for things you wouldn't normally try.
Some things I have learned.
White glue makes a very good tie dye (or cold process spray on dye) resist. It is cheep easy to use and washes right out.
Model magic makes wonderful facial appliances like stick on ears and the like but it crumbles easily if not reinforced.
Clear nail polish dose not get along with model paints.
You can sew through fun foam for things that need to be riged and flexable at the same time.(Like big fluffy bows.)
Metallic acrylics especially the gold do not play well with heat. I think it is the copper they contain.
Dry cleaning kills heat and bond and can make the adhesive seep through and leave nasty black marks.
Plastic netting makes for excellent under structures for armor but if you use it with thin fabric be prepared for the whffle like pattern to show through.
Sharpey dye works for ribbons as well as it does for synthetic hair.
Hook and eye loops make for very good laceing loops.
Wiggele eyes make for exelent rivits once they are painted.