The main problem for a beginning writer
To an extent all writers are beginners with each new project. Sure, the practiced hand will generally know more from experience about what choices work better than others. But he or she, faced with a whole new story and sketchy characters, inhabits the same intimidating shadow world as the novice storywriter.
Confidence does come with experience, but in varying degrees, depending on writer and project. The impulse to remain safe, to not take a chance, is human and understandable, but it's a creativity killer, manifesting itself in keeping a story preciously in the head instead of dealing with the inevitability of warts on the page.
About the only way to lower the fear of writing a story (lower, not eliminate) is to commit to putting words on paper, and to keep doing it pretty much on a daily basis. By writing, writing, writing, a workable story will emerge from the mist. It'll change a bit from the heretofore brain-locked idea, but it will begin to take form and demand further expression.
A writer's muse starves on timidity, and thrives on The risk of trying the adventurous—even seemingly outrageous. At the risk of feeling inadequate and stupid at first, a writer can eventually find inspiration by trusting, even with a stretch, what could be—by embracing Story as Possibility. More
