There's no correct answer here. However...
There is so many ways to identify an area for improvement and definitely depends of the kind of job that you apply for.
First of all about jobs that are related to public sales, and customers. You should pay attention to the little thigs, the details. And here you can Quote Malcom Gladwell that in his book The Tipping Point said that little thigs can make a Big Difference.
- Your Body language: Remember you have to proof to other people what you are capable and how you can handle troubles and issues that would present to you in your work. So in first interviews you have to be calm, but at the same time show strength and capability of work.
- Your Message: It has to have a stickiness factor. Simple but strong enough for your interviewer to remember you from the other applicants.
- Finally but not less important DO YOUR HOMEWORK: Get involved in the part and process of interview and study some facts or information that your interviewer would cheer, such us the organization of the company, the number of sales, the profits or certain data that would help the interview to choose you because he thinks that you are already a part of the bussines.