Unless you have a background in sales, pulling the right information from sales professionals can be challenging. To level the playing field, here are five questions you'll want to make sure you ask every sales interviewee.

They say you can't teach an old dog new tricks. Although it's possible to retrain sales professionals, it's likely that their prior sales experience and performance will carry over to your company. So when you interview sales reps, you should look for people with a proven track record of selling the way your company sells its products or services. Specifically, there five questions that you need to ask during every interview.

"What is your sales volume?"

It's important to know how much the candidate is capable of selling. There is a big difference between a sales rep who routinely sells $5 million a year and someone who sells $500,000. Along the way, you should also try to find out how much they sold during their best year, and whether they met their sales quota last year. If they didn't, you may be talking to someone whose star is falling – not rising.

"How many sales did you make last month?"

Sales frequency often provides more insight than sales volume. If the candidate is used to making just a couple of big sales each month, he probably doesn't have the experience or skill set to routinely rack up dozens of smaller sales – even though the monthly volume quotas may be the same. The issue isn't whether or not he is a good salesman. It's whether his background has adequately prepared him for the kind of selling your company requires.

"How would you describe your typical client?"

Did the candidate sell directly to consumers, or did he sell exclusively to other businesses? Was he regularly in touch with CEO's and upper-level managers, or did he primarily work with lower-level purchasing agents? Sales professionals develop a style and demeanor that is tailored to their clients' needs and personality types. Over time, they become familiar with their clients' concerns, motivations, and buying patterns. If the candidate hasn't ever sold to the kinds of clients your company deals with, it may be difficult for him to make the transition.

"How do you generate leads in your current position?"

Lead generation is a skill that is learned by experience. These days, it's not uncommon for the lead generation function to be farmed out to someone else, leaving the sales rep free to focus on moving clients through the sales cycle. If your company requires sales reps to generate their own leads, you need to know that he can sell without being handed a list of pre-qualified leads.

"Could you describe your current sales cycle?"

There are often variations in sales cycles from one company to the next. Although the variations may not be dramatic, you should pay attention to signs that the candidate is accustomed to a longer sales cycle than the one you expect your sales team to follow. It's possible that the industry in which the candidate currently sells demands longer selling cycles. But if your company is situated in a short cycle industry, you could be setting him (and your sales team) up for failure and frustration.