This may seem like a no-brainer question, but just how well do you know the services you offer? If you have a large insurance agency, you may offer many services that vary per policy sold. Do you have a complete grasp on all of those services and can explain them in detail to a customer who asks about them? If the answer is no, you need to do your homework.
You cannot successfully sell complex goods, such as insurance policies, without also offering service on those policies, whether that be handling a claim or explaining what is and is not covered. In other words, you need to know each policy and all your services intimately to allow you to answer any questions promptly and thoroughly.
People who want to buy insurance from you need to know that you know what you are doing. If you cannot explain your services or are vague about what you offer, they are going to notice, and you stand a good chance of losing a sale.
Never assume you know all there is to know about every policy. If you sell a policy, make sure you read it, study it, talk about it, know everything there is to know about it and be able to expertly handle any questions. The growth of your business depends on it.