so my attention span is... not.. great....... so forgive me for skimming this and picking out the bits that Spoke To Me
also, before we start, WELCOME TO TAPAS!

there are lots of places to learn all this lovely juicy stuff!!!
i recommend, as a first port of call, scott mccloud. hes like, forgive me will eisner the father of comic theory and comics about comics. he has three comics that talk about comics - how to make them, what they are, where theyre going, their history. all sorts of lovely jubbly nerdy stuff. youll hear me and others like @niah146 gush about scott mccloud... regularly.
understanding comics is his first book, its a great introduction to the medium - it introduces lots of concepts abt the mechanics of comics and the nature of panelling and panel transitions, and then spins off into history and wider art theory and lots of stuff. i first read it about a year ago when i was just starting to take comics seriously, and it blew! my mind!
then theres reinventing comics (harder to find online, but look in your local library), which looks more into comic history and potential for the future. also an inspiring read, but a lot of its a bit dated.
and then making comics, (you can find it online if u rootle enough) which could be a good start for you - it covers the basics of actually making comics. i havent read this one yet, but ive heard its a really good beginner crash course.
besides that
1: look around the forums, people often have discussions about panelling, composition, word bubbles. @SleepingPoppy beat me to mentioning the nitty gritty tips
rude
2: look at comics you admire, and applying what you learn, study what they do. and copy it.
3: ask!!!!!!! you can always ask for feedback or advice on the forums, and theres lots of people that will help you out 
tbh i think writing on your own is the best thing to do when starting out - to be crosstrained in the art and writing of comics is a really good thing, and doing all bits yourself makes for smth harmonious (not that collabs cant also be harmonious, but it takes more time and experience to mesh)
and yknow what? every writer is a shit writer to begin with. hemingway? there was a time when hemingway couldnt write for SHIT. SHAKESPEARE? that dude couldnt even READ in the very beginning (yknow, bc he was a baby). everyone starts somewhere, and you learn how to write by writing. and reading. read. read a lot.
totally definitely absolutely start with short stories and short comics - and have fun with it! pick stuff you arent too attached to, fun weird ideas to fuck about with. derivative structures, worlds, stories, characters... just do something short you can crap out and move on to the next thing, and experiment as you go. if you see something a writer or comic creator does that you really like, steal it, whack it about, see what makes it tick, and move on.
you will never be ready, in your opinion. definitely start slow and small, ease yourself into it - do not start with a 5000 page epic. please dont. - but do just start. the first few things you make are allowed to be entirely awful, theyll be yours, theyll have that glimmer of you that youre gonna polish as you go until it shines.
someone on the comic podcast 'dirty old ladies' (highkey recommend, btw) once said "everyone has 200 awful comic pages inside of them, and the only way out is through." so start, and embrace the crap because its part of the learning process.
be derivative!!! fuck it!!!!! everythings a ripoff of something else!!!! the handmaids tale is a ripoff of 1984, the lion king is a ripoff of shakespeare and the bible, star wars is a rip off of ninja(? kung fu? kinda thing) movies, narnia is a ripoff of the bible... ya get me?
that said, your inspirations are all very popcultural. this is fine and good and great, but id recommend widening your scope, it could solve your dilemma here. look into what influenced the marvel or overwatch writers - what stories inspired them? and what stories inspired those stories? and what stories... etc. read some classics, watch some old movies, look at some art. read some mythology. read some psychology. talk to people. steal their stories. add some funky scifi junk. make it your own.
the key to originality is a wide pool of references. its not about an all new ingredient, its about a new recipe.
then keep it! that advice is for people further down the line, looking to take their comicry into a career. and there are plenty of comic artists who do really intricate, painterly work - in webcomics, and working for marvel and DC. the only way for you to know whats best for altering your style, imo, is to get working and get experimenting and see what you like
at this point, dont make comics for anyone else. dont think about target audience, trends, demand... whats the story you want to tell? how do you want to tell it? do that.
draw out a plan of the entire plot before you really start. this means you can work out the kinks, figure out the order of things, and select from this wide array of events a good place to start.
look at how other stories do it! how do your favourite comics start? your favourite movies? look into story structure and read stories with good structure and pick apart (and steal) what they do.
like, basically, yeah
that sounds like a really good start
look into other media that goes for that tone, and see what they do.
its really cool to see someone so passionate about comics, i really hope my advice and these forums help you on your way
ill always be happy to give feedback or advice on anything you post here!