There are lots of character traits and habits/behaviors that contribute to being a good Account Manager, but in this day and age there is one simple thing that all salespeople, regardless of talent, can do to separate themselves from the large majority of their competition: they can do what they say they're going to do.
We have been conditioned to almost expect people to not do what they say they are going to do, so when people actually do follow through on their commitments, when they actually do follow-up when they said they would follow-up, when they actually do complete the big -- and little -- tasks they said they would complete coming out of a meeting, it is like a refreshing surprise.
If I was a whiny, grumpy old man I could dedicate the next couple of paragraphs to shaking my fists at the world and asking "Why? Why has the bar been set so low? What is the world coming to? This isn't right!!!"
But I won't. Why would I? If I do what I say I'm going to do, and all the people on the Varrow sales team do what they say they're going to do, we will continue to surprise and please our customers without doing any more than we would expect of ourselves anyways.
If this is the baseline from which we start, and then when we do all of the other things that go into being great account managers, we go from being a refreshing surprise to a truly valued and trusted business partner and friend.