I think making a costume which accents your body type is what takes cosplay to the next level. It fits tightly where it needs to be. It fits snugly where it needs to be.
After all, clothes are just there as a tool to upgrade your appearance and likewise for cosplay.
The most defining characteristics of anime character or anything are their curves.
Some other things I notice at cons are wigs that shine too brightly.
Just being attentive to details and getting the common things right makes a great cosplay. C: