Create a template of butterfly wings, make sure the size is about right and you have seperate upper and lower wing parts.

Either just print them out and blacken the backside of the paper with any given marker/pen. Paper makes this really light and easy to work with, but you may not be able to reuse them.
Or use thin black cardboard, they get heavier and sturdier.

Cut your wings out using an exacto knife or anything else you find usefull.

Optional: You could try and curl the wings a tiny little bit, just to make sure they won't touch your face all the time. I bended the inner tips upward a little.

Apply your desired makeup. Either go for dramatic black and blue glamour or - which is what I did - apply light, soft colours with a shimmer.

I also used black liquid liner to create my usual eyeliner routine, and I also added a thin, jerky, squiggly ( would not know how to describe it otherwise ) line going upwards from the outer third of my lid. Obviously. Aaand I added tiny dots. Because I love dots. ;)

Get your lash glue and glue the inner tip of the upper wing to your upper lid, close to the lashline. Hold them in place untill your glue has dried.

Place the lower wing tip just below the outer edge of your lower lashline.
Sorry for the crappy image. :D

Basically you're done now. Of course this will feel a little weird at first and you should make sure your don't wipe your face by accident or get your hair all tangled with the wings.

But there's one more thing I'd suggest: Get in front of a mirror and blink! Just blink. And look what happens. <3