I have interviewed hundreds of candidates for open sales positions and I must say that out of 100 candidates, only about 10% have prepared themselves for the interview. This is quite disappointing when trying to find a sales professional for a job, but you could look at this as advantage by preparing for a job interview.
One of the most important part of the hiring process is the sales interview where the hiring sales manager asks questions to learn more about the candidate. Now it is important to prepare, but many prepare wrong. What I mean by this is that, people search for interview advice such as how to answer specific interview questions, and when they are asked the question, the answers given are generic and sound scripted. To me, I can recognize this right away and it doesn't really help me understand the candidate's unique ability or experiences.
Now a better way to prepare is to learn how to formulate common interview questions to communicate your unique skills without sounding scripted. You add your personal flair to your answers to make them your own. Remember, these questions are asked to learn about your experiences and how you would approach situations. If you do not have a direct experience with a question, you can use other experiences that is not related to sales to use as your answer.
When you pull from your past experiences and approach, you bring to the table your unique skills and this makes things really interesting for a hiring manager. For example, when I ask the question, "tell me about a time when you have encountered a tough customer that had high potential but didn't want to buy from you". Now you can find the generic answers to this, but I am really looking for how you would approach this and add in your own experiences you have had in the past.
So, if you ask, how do I handle tough sales interview questions. Try being honest and give your personal professional experiences and make the answers your own. Do research on how to formulate it to communicate the information succinctly, but don't try to memorize a generic answer, because, 10 other candidates will come after you with the same dull answer.