Okay, we all know a story should have a beginning, middle and an end. Not all stories or novels should follow a formula but many of the classics do (in a very disguised and sophisticated fashion).
With my 'modern teen classics' series I have the basic outline or story arc from the classic novels of Jane Austen: (Pride & Prejudice/Pride and Princesses & The Hotness), Emma (Popular), Persuasion (Truly) and Emily and Charlotte Bronte: (Wuthering Heights/ Wuthering Nights and Jane Eyre/ Anne Eyre).
These brilliant, classic writers created memorable, lasting stories that have been adapted in different forms by hundreds of movie makers, publishing houses and writers throughout the decades.
Are they formulaic? Jane Austen is in some ways, she's great formula but she had a formula all the same. The formula was the obsession of the day - a woman, single at the start, seeking her fortune in the form of finding the right man.
Jane Austen's stories have strong female characters, "hot" but difficult men (er, Darcy anyone?) and happy endings - in the main - marriages.
Emily Bronte was probably the least formulaic of the writers I've mentioned, in the sense that her main characters (Heathcliffe and Cathy) do not have a happy ending in the traditional sense. The story is also metaphysical and mystical which was quite unusual. Charlotte Bronte's Jane Eyre only gets her 'happy ending' after an incredibly tough childhood and early adulthood. Jane Eyre is bittersweet - a lot has been lost before much is gained.
If I were creating an entirely original story I would keep these lessons in mind from these great writers: bold characters, a strong beginning, some action in the middle and a powerful ending. To create a story arc that other people want to read you have to have a real sense of what you want to write about, how the places look in your mind, how the characters speak and what they say.