so I had to take a few days to think about this one
here is the worst piece of advice I can give to an aspiring writer:
Wait.
that idea you have in your head? don't work on it yet. don't put anything down.
wait.
what if you lose interest and run out of steam halfway through? then you'll have wasted all that effort and learned nothing! better to wait it out for a few weeks, to see if the interest is still there. and even then—
wait.
wait before you tell anyone about it. don't get anyone's hopes up! don't give them any ideas, either! better to maximize the force with which your idea will strike the world once it's good and ready and you can just sit down and bring it to life in one glorious go!
but until that day comes,
wait.
this has been a retelling of the biggest mistakes I've ever made as a writer and just so we're clear you should never do this. put your thing out there!! scribble every last little idea, share it, let others pick your idea up and give it a ride somewhere new and help it blossom into something it could never have become if it had been confined to the head of a single person! ideas are worthless, executing on them is the most important part. so let's get to it, as soon as we can. good luck! I'm rooting for you <3