Pretty much the first thing you want to do when beginning to cosplay is to find as many images as possible of your chosen character. This will help with the planning stages so much that it’s impossible to leave out. Good references will get you far.
Luckily, this year at Blizzcon, they revealed this amazing statue of Sylvanas, and it’s super detailed in every way.
I’m using it as my primary reference for this cosplay. There are lots of versions of her armour, but this one with her War Garb is my favourite right now. It also means I’m able to cosplay within my personal comfort zone, as my “rock hard abs” won’t be on show.
Depending on what your chosen character is, there may be a lot of sources, or very few. I’d suggest doing a roundabout google search for your stuff:
Adding ‘cosplay’, ‘costume’, ‘cosplayer’, ‘artwork’, ‘reference’, ‘patterns’, ‘tutorial’ are some of the buzzwords you might need to add to your search after your cosplay subject’s name.
I’d definitely check on sites like Pinterest, Deviantart, Tumblr, and YouTube tutorials for your cosplay. There are a whole load of different places to find reference material.
For some cosplays, there are actually really helpful resource packs from teh publisher. Blizzard in particular have awesome PDF kits with great breakdowns of their key characters for the sake of cosplay. You can usually find these by looking on official sites. The one I’m looking at for Sylvanas is from Heroes of the Storm, so it’s not 100% accurate for the particular version of her that I’m planning on.