Self-doubt is a terrible beast that plagues a lot of writers. Every writer probably has their unique spin on it, but it seems to usually boil down to not being “good enough.”
First of all, that’s just silly. Of course you’re good enough. If you weren’t, the story wouldn’t have chosen you to tell it.
Writing takes a huge amount of trust in aspects of life that aren’t tangible. You have to trust that you’ll convey the story in the way it wants to be told (here’s a hint: you can and you will). You have to trust that if the story does begin to go astray, it can and will be caught further down the line. It may end up being stronger from the jaunt. You need to trust that vision that started you down this road to begin with. You need to trust that it won’t lead you astray, no matter what.
Trust is a hard thing to hand out, but out of all the things in life you can choose to trust, yourself and your dreams ought to feel the safest. Embrace it and it will love you right back.
I talk to a lot of folks new to or struggling in the writing world, and they almost all want to know how I get past writer’s block or find my way out of corners or fill in plot holes. The only advice I can give – and it seems like something that is hard to accept until it clicks – is to trust that the story and your characters know where to go, and to let them. Don’t worry about being “good enough” or “doing the story justice.” Not in the phase where you’re worrying about writer’s block or corners or plot holes, at least. The spit shining comes well down the road. For now, just write.
The moment you can turn off the self-doubt (and unfortunately, it’s something you’ll probably have to do more than once, so it’s best to get used to doing it as soon as you can), beautiful things will happen. You will always tell your story better than anyone else can, so let yourself write it and keep faith in the journey.