There is no structure in general that guarantees a high mark. An examiner at AQA will look for original ideas, applications of various language and structural techniques, and also an emotional and spatial focus. One very common piece of advice in Paper 1, Q5 in particular, is to introduce and describe (setting and atmosphere), zoom in (Focus on sensory details for a specific character(s) or object(s), zoom out (Refocus on the story, engaging in a character's actions, with a focus on how it affects the overall atmosphere), and then to conclude. An important thing to keep in mind in descriptive pieces and narratives is that examiners (and readers, at a professional level) will look for a masterful control of spatial and atmospheric elements. Put simply, they want to see a writer that knows how to use an atmosphere, environment, and mood to make the reader feel exactly the emotion that the story is written to evoke. For example, a writer that wants to evoke some pity or sadness may attempt to make the atmosphere bleak, and dull, while also focusing on individual character movements in a slow fashion, while a writer trying to evoke joy would involve colour, lots of activity, and fast, active scenes (But not too fast to the point where it feels angry). Overall, the best suggestion is to adapt your personal writing style in order to include how you best feel comfortable in incorporating a suitable atmosphere for your story/descriptive. As I'm sure you can tell, I'm more of a narrative person, hence my narrative involved tips. However, if you feel more comfortable with descriptives, this can still be applied, it just has to be reworked in order to make the narrative less of a focus.