>>18709213Just write.
Usually I come up with a plot after I get my premise. But the important thing to do is write something every day. If you're serious, don't end up like those people who just come up with ideas and storyboard all the damn time but never write down a word, only to drop their story some time later in favor of the next big thing. What you write doesn't have to be good either, just write a little bit each day and you'll improve.
So think about your plot (or PLOT), since you've sort of got a premise. Then just write an opening paragraph or two. Don't stress too much about it flowing together, just write what you want to happen. Close your document and let it sit for a day. Come back to it, revise, and add some more. Take care not to delete the whole thing and start over while doing this because you need to keep your base work for the next step: post the revised stuff here or somewhere you can get some critiques. You might get a lot of hate for what you write, but don't worry about it. So long as you can get an idea of what people like and don't like about your writing, then you know what to try to improve and keep when you revise again.
That said, for fanfiction, your writing doesn't need to be phenomenal. Just make sure your spelling, grammar, and syntax aren't absolute shit and you'll probably be okay. I'm sure someone else with more writing experience can add on or improve what I had to say, but I hope I helped and actually touched on your question.
