The first one is the basic idea, on which the story is created, that is something that makes it special, possibly original (although it is not essential at all), but always unique.
The second one is the writing style, which like the brush strokes of a painter gives colour to the story thus bringing it to the light. It concerns the use of a given language and the tone in which it is used. With the word style I don’t mean, therefore, spelling and syntax, which I take for granted.
The third one is the way it is narrated, i.e. the whole of narrative techniques used in presenting the story to the reader, for example, points of view, plot twists, flashbacks, the red herrings, cliff-hangers, beginning, ending, prologue, plot points and a bunch of other tricks, some of which do not have a precise name, which influence the structure of the story, regardless of the basic idea and the style.
Even if the ideal novel should have a good basic idea, a just as good style and should be narrated in the best possible way, of these three elements, in my opinion, the most important is actually the third one.
Think about it for a moment.
Suppose you have fantastic idea, which no one can resist. Suppose you write with an impeccable style, which is fluid, maybe musical, strongly evocative, and able to enchant the reader.
But suppose you do not know how to use these two elements to narrate it in the right way, choosing the most appropriate point of view, interspersing scenes in the most compelling way, measuring the length of the scenes so that they are neither too hasty or too synthetic, inserting plot elements in the right point that leave with bated breath, trapping the reader through the pages of the book from the first lines or leaving them satisfied when reading the latest ones and so on.
Suppose you lack all this or large part of it. Do you think your book will appeal to the readers? I do not think so.
Now imagine that you have an already heard idea, really not original, you write in an acceptable style, but nothing special, but despite all this you are a real master in building the story. You handle with great easiness the various narrative techniques, you are able to capture the reader from the first words and not let them go until the end. Indeed, as they close the book, satisfied, they can’t wait to read the next one.
It is clear that you have everything you need to make readers love you (and maybe become a successful author).
Maybe the readers (and authors) who are a little more delicate (snob?) would turn up their nose; they will say that you are commercial. The truth is that most readers are not nearly as pretentious as them and you want to reach all of them. Well, the good news is that you have within you the most important thing you need to succeed.
The big bestsellers show us that it is so. I mean both the good ones and bad ones (according to a subjective point of view, as always). Some of them will be able to rely also on the other two elements (idea and style), or at least on the second one, and so be good. Others instead will totally lack a good idea and a good style, or at least the second one, and will be bad. But almost all (there are always anomalies), some more and others less, will be characterized by a solid narrative structure.
Where this is lacking at all, you will have an aesthetically beautiful written text, perhaps with a unique idea, but which fails in the attempt to satisfy the reader, which is its ultimate goal. In the end it is so also for those who say to write only for themselves, but then publish their writings or at least let them be read (so obviously they don’t just do it for themselves).
One can argue that there are past examples of authors who gave a little less importance on the development of the plot, focusing just on style. I could think of Virginia Woolf, in whose books very little happens, but everything is narrated by mean of the beautiful stream of consciousness. In this case, however, I would let you notice that the flow of consciousness is in fact a narrative technique (i.e. it falls more in the famous third element than in the style). And anyway none of us is Virginia Woolf or James Joyce, but most of all we do not live in their time. Readers now look for something different, we must accept it.
This is perhaps a trivial consideration, but if you think about it, sometimes it is put a little aside. The emphasis is very much on style, on the correctness of language, on variety in the use of language, but you forgot that the writer must first of all be good at telling stories.
If this ability is lacking, everything else is useless.
Of course, if this supports an original style, capable of arousing pleasure in reading, but without taking the whole scene (the best style is the one that you do not notice consciously, while you read, because you are too caught up in the story to really notice it), the result will be a great novel (or novella, or short story).
Eventually the least important element is precisely the idea. If you notice it, books constantly feature hackneyed ideas, yet many of them are widely appreciated by the readers. This is because the author that knows how to use their own style and especially the narrative techniques has the ability to take an already heard idea and make it his own, present it again to the reader in a completely new version, able to move much or even more than the first time, in which this has been used.
I believe, indeed, that the best authors are the ones that are able to take advantage of the old ideas, accordingly attracting with ease readers who like them, however producing a written work that can surprise and touch anyone who reads it.
Of course, this matter is much more complex than that, but the reason why I decided to talk about it is because I often stumble across books that have precisely the defect of being poorly told. And I have to say that it is sadly very well-known in Italian authors (i.e. from my country). Not surprisingly, while the books of non-Italian authors, coming from any country, are imported with ease in mine, as in so many others, just because they have this universal element to be well told (again, there are many exceptions), it is not just as easy to see the opposite phenomenon, and when you see it, you can bet that it concerns authors who handle with ease the main narrative techniques.
I honestly don’t know the reason for this Italian lack. The consideration that, however, I want to draw is that, in my opinion, all writers, even the snob ones, who want to become really good at it, instead of fossilise on too many alternative readings, should read these bestsellers and try to understand what in the way in which they are constructed makes them sell.
It cannot hurt; in fact, there’s always something to learn.