Three ways readers will judge your work
There's no guarantee that readers will like your work – in fact it's a rule of thumb that 20% of people will hate it even if it's genius. So how can you be certain that those 20% aren't right? How can you have any confidence you're not serving up a load of tripe?
You can't – all you can do is get your ideas and story across and let the readers judge your work for themselves – and here's how they're going to do it.
Is it believable?
So the mild-mannered janitor suddenly kicks some kung-fu ass two thirds of the way through the novel? Give over. Darcy reveals at a tea-party that he can break-dance? Please. A lone cowboy is about to take down a whole town of banditos when the swat team arrives? Right.
Some extreme examples to make the point but it's still a point. Essentially there are three areas where your story will need to be plausible – character ability, character action, and plot. If your character is a hairdresser who can also drive an HGV and is a crack shot with a Lee Enfield you'll need to set that up before you exploit it. It will also need to be convincing how he knows that stuff.
Character action also has to be believable – how many times have you watched or read something and said to yourself 'why the hell doesn't she just call the police/lock the door/cry for help?' Robert McKee points out that a character will always take the path of least resistance to get what they want. Observe that rule and your characters will always behave plausibly and convincingly.
Is it coherent?
'I'm not sure if I liked that or not because I didn't understand a bloody word of it,' is not something you want your reader to be saying after finishing your work. You can't really expect them to have an opinion if you haven't expressed yourself with clarity, if there isn't an end to your beginning, an answer to your question, or a method to your madness.
Coherence relates to structure and plot, the framework of your story, the spine of your narrative. If your scenes progress consequentially i.e. each one is a natural consequence of the preceding events – then there will be coherence.
Coherence also relates to expression and voice – is your story being expressed clearly, your choice of language specific and revealing; does your voice have authority.
I'm using a lot of words where only one is needed – craft. Go get some.
Is it conventional?
Nobody likes to think of themselves as conventional. Nobody likes to think of themselves as conforming; everybody likes to think they come to a movie or book without preconception – but it's all nonsense. People come with a whole heap of baggage to a cultural event. They will have genre expectations even if they don't know it. I see a murder in scene 1 and a detective in scene 2 I'm going to expect that copper to solve that murder. If I see 'Day of the Dead' on Monday, and 'Shaun of the Dead' on Tuesday – I'm going to make comparison. I read Stephen King I expect to be scared, I see an action movie I expect some dudes to get shot.
Convention isn't a bad smell, it's your friend, and the yardstick by which you will be judged. If you don't like it try mastering it so you can transcend it or break it. Either way you can't ignore it.