The kind of short story that gets a good reaction is the story which has a positive ending, particularly when the better side of human nature triumphs despite the odds against it. Many readers enjoy seeing characters like themselves overcoming everyday problems with an unexpected twist to them. They do not usually like stories which sadden them, or which make fun of others. Laughing WITH the character is fine, but never at him. Avoid religion. Take it from me, even with the best intentions you're bound to annoy someone if you don't.