I'm planning to do a Ranmao cosplay.  You know that quiet girl from Black Butler?  XD I love her so much, and I would think her costume would've been easy but those butterflies....any ideas on how I could possibly do them? 
Please and Thank you

The butterflies on the skirt/dress right?  We have done things like that by using freezer paper stencils and fabric paint. 

First cut out freezer paper so that it is a stencil of what you want, in this case a butterfly.  Then once you have the stencil you'll be able to iron it to your fabric.  Then just paint away.  Please note these stencils aren't reusable so take that into account. 

it is an iron-on "glue" you can use to fuse 2 fabrics together.  I took reference pictures and blew them up on my computer to the size I needed it to be [measured the skirt to find # of inches the design should be] and used this as a stencil to trace it on to the papery side of the heat n bond.  iron 1 side to the darker purple, cut out the butterflies, peel the paper off, then iron onto the dress. 

Also dont use the "lite" version, it wont hold as well.  you can get it at walmart or joanns that I know of. 

Edit: make sure you get the orientation right before you actually cut it out, you might need to mirror the image / flip over your stencils, I forget, but I always triple check before I cut

I second heat n bond.  But to add to what was said, I would then applique it down.  That keeps your edges from 1) fraying and 2) coming up.  It doesn't happen often, but it's safer and it makes for a very pretty, finished edge.