When you write a short story, you have to try and set the mood as soon as possible to draw the reader in before the story ends. Long stories such as in novels take their time since they have pages and pages to fill and you slowly absorb the mood in a more leisurely pace. You can use dialogue such as, "I told you never to set a foot in my house again, you lousy cheat." It pretty much says the story is about a fight between husband and wife. Or you can use descriptive words such as, The heavy air under the weight of the slate blue sky pressed on my thoughts, making me feel small.
Mood is the emotions that you (the reader) feel while you are reading. Some literature makes you feel sad, others joyful, still others, angry. (Tone and Mood) You can also call it the atmosphere of your story. Words paint feelings on paper. In my story, Idiot Thieves, I start the story with the sentence, "My day started as normal with my getting up and getting the coffee brewing for the morning, taking a shower and then feeding the cat." It shows a pretty normal person going through their humdrum morning ritual, setting the mood for a later surprise. In another story, My Secret House, I use the line, "Where shall I start?" to show a complicated situation around a specific incident.
When I try to think of story lines, sometimes I will hear someone say a phrase that will be enough to get my imagination going, but often it is a picture that really opens the doors of a story for me. What works for you?
My latest story, Who Am I? came from a photo I took while vacationing in Seattle of a raging river. Somehow, I could imagine a person trying to white-water raft through the seething water and my story starts, My first thought I remember was, “How can I get out of this water?” but it was more of an instinct than a collected thought...