It is definitely important to take into account surrounding factors when trying to write a good short story analysis. The factors you are pointing out in your question are without doubt the most important ones to focus on if you wish to be successful in producing a good analysis. I will explain this in more detail for two of these: preparation and mindset.
With regard to preparation, it should be obvious that this is crucial to writing a successful short story analysis. After all, how would you know what aspects to focus on if you have not prepared yourself sufficiently and don't know what to cover?
In order to write a good analysis, you should definitely prepare yourself in advance by revising the various things you could focus on in your work, such as plot, characters, themes, writing style, the use of metaphors and similes within the story, and so on.
With regard to mindset, I think it is important to realize that you will only ever be able to write as good an analysis as you are willing to write. If you are under a lot of pressure and stressed, you might be tempted to rush your analysis. This could result in a very superficial analysis, neglecting to go into sufficient depth. Therefore, in order to use mindset to help you write a good short story analysis, I would suggest that your mindset should be a mindset geared towards success, wanting to do your best and putting 100% effort into your work. Growth mindset is also very important in this context—if you have written an analysis in the past that wasn't very good, you shouldn't be disheartened; instead, you should see this as a learning opportunity that allows you to learn from your mistakes and to improve in the future.
In a way, mindset is therefore also linked to preparation: for the highest benefit, preparation should also include looking at previously written work, seeing what you did well (which you should then try to repeat in the new task) and seeing the errors you made (which you should avoid repeating in the new task).