Do it anon
I did it and it was so reliving and now I can finally live my little emo dreams
The worst thing that can happen is you fuck up your hair but unless you're balding/prone to losing hair you'll be fine because hair always grows back but in case you're extremely nervous about fucking up, buy a back up plan, aka a wig that you can wear for daily use (but i doubt you'll mess up that bad)
I'm not any sort of hair professional so take what I say with a grain of salt/caution. Everything I learned is via reference images and YouTube videos (which can be very useful)
How I start off is I style the way I want my hair to look, push bangs to the side I want it to face, put the side hairs on my cheek, just a general/basic shape and then I straighten it till it is flat.
My hair generally has alot of volume to it so I prefer to trim alot of that off to lessen the poofyiness of the style and make it more sharp/edgier.
If you have bangs the recommended height imo is a little below your eyebrows is how I do it personally because I like my hair in my face.
If you don't have bangs I would cut them into your hair. Makes it easier to style the hair style but I know some don't like them, that's just the way I personally do my hair.
I grab a razor (a leg razor because I'm poor) and just start going bit by bit trimming off hairs making it more layered and use a pair of normal hair scissors to clean up anything that needs clean up.
Getting that really big poofy hair for the back is simply just teasing and hairspray. Would include extensions for your hair to give it that look and of course straighten it.
Kind of a shitty explanation but again, watch youtube videos, it's worth!! Remember, the point of the hair style is for it to look choppy.