Good salespeople have good answers. Great salespeople ask great questions. Ask open-ended questions and then repeat their answer back to them to get your prospect to feel understood. This also helps because it allows the prospect to clarify something you may have misunderstood or assumed incorrectly.
If you are confident in your abilities and are a good communicator (i.e., you listen well and know how to encourage others to give you more relevant information), you will do well in sales.