How good are you at once you identify something about someone then managing expectations. That is basically the best summation of maintaining an account t I can give. This also applies to employee’s.
Ask what can I do for you?
It would be useful to read certain self help books and get up to speed on major personality traits and how they interconnect then how you might interact with them.
I’m of the mindset just find the path and do only that path then just expect that much. If their sales are only on a friday - dont go in on a tuesday and then complain. How can you know they’re busy on a friday go look on google places and see when their foot traffic is. I’m not going to offer them $30 5lb bags and then hope they move crazy volume when they’ll order one 5lb bag in a month because they have one busy friday night or on the other side they're being super cheap.
Don’t think they’ll be something more than they are. If you vetted them enough you’ll know basically what you can expect.
Every account falls into these family based patterns: We all have that late arriving family member. Don’t expect them to get orders into you on time. We all have that angry uncle or aunt. Don’t go into that account and expect them to be kind to you all the time. There’s always the quiet brooding one who wont say anything but if you do something then you’ll hear all about it. There are always demanding parents or grandparents that will ask for far more than they give. Why aren’t you demoing 5 days a week. Why aren’t you moving 100 bags like this massive roaster. Maybe you have a cousin you get along with really well and are fairly close for awhile but then things kind of drift apart but you still text or email occasionally and overall things are ok. Maybe there was a brother/sister in law you got along with well but things fell apart due to outside circumstances so you never see them again. Accounts are exactly like this.
In general the best advice I have is to communicate in person as often as possible without being annoying.
Don’t waste time but also don’t be silent. At least for the accounts you really care about.