As a Field Sales Executive you will have had some previous Sales experience, maybe in a similar industry or product line or maybe even a role on the road and a different industry. Whatever your experience you will need to be good at selling. Your communication skills will need to be second to none and you will need to be very motivated and confident.
Before attending your interview you need to know what area you will be expected to work, how far is it, how achievable are the results? You need to analyse what the company is all about, can you find out what other sales people they have or what the company team size is etc?
Related: Sales Assistant Cover Letter
As a sales person in the field you will need to be prepared to travel some miles each day and depending on the size of your area you may have to stay away one or two nights a week. With previous experience you will know that a sales environment is not always easy and that you need to be prepared for rejection and be self motivated to keep bouncing back up.
When you have assessed where your interview is going to be held and basic details such as parking etc then you need to analyse your skills and against the job requirements and prepare practice answers as to how your experience matches up to what they are looking for.
During your interview, you could be asked questions such as:
What products have you most enjoyed selling and why?How do you feel about working to targets and how have you worked to targets in the past?Can you sell (XXX) to me? They will be looking for an example of your selling technique so research their products/services.How do you keep motivated?As a sales role there are many job specific questions that you are likely to be asked but you need to go to the interview fully prepared and if you have done your research that will help a great deal.
Best of Luck.