As we've seen it's important to show your readers where and when the story takes place. This can be done in a number of ways either by showing through dialogue and action. Or by telling the when and where in passages of description. The following things are good to keep in mind when you're revising your story.
Have you established where the story is taking place preferably by the second page of the story. Having your characters exist in a vacuum might work if you are writing a science fiction story or even a horror tale. One of the first editorial comments I received was "Your characters are existing in a vacuum." The editor was kind enough to add a few brief sentences to show me what she meant. Letting the readers know where the story is taking place is important and each time you move the location, you need to show where the characters are.
Putting the bits about the where and when of the story into the first chapter helps. The readers want to know this. Think of how hard it would be if you were reading a story and learned this was taking place in the present or the past or happening in a hovel when you thought a palace. Doesn't take much to tell and show where the characters are situated and when in history they exist.
Another thing to be aware of is giving the reader a picture of where a character exists of the social structure. Matters are different for the rich or poor, for the servant or the owner, for the doctor, the nurse or the patient. Consider all these things and show and tell the character through action, dialogue and description these things.