Add spikes and/or studs. These will definitely add a huge edgy touch to your outfit and there is a huge variety of studded/spiked items out there so, have fun and make your pick!
Tip n°2: Add a bikers jacket:
This is a clothing piece that can make a sundress look edgy.
Add this to any outfit and you've made it edgy.
Add metallic pieces.
Demi Lovato is an expert at this trend and pretty much anythhing she wears is edgy.