Communication is the most important aspect of any role in a real estate transaction. A good loan officer will proactively keep you informed at all stages of the transaction, and provide respond to your questions in a reasonable period of time (we are all busy, but should be able to respond within a few hours, a day at the absolute maximum.) Being knowledgeable and having a good variety of products to offer (FHA, conventional, 203K construction loans, etc…) is also important, and a professional demeanor is a plus, but ahead of all else is their communication skills.