The first mistake marketers make is that they want more. More customers, more noise, more ads, more shelf space, more customers, more customers, more customers…
Almost all of their actions are driven by the search for more customers.
The reason this is a mistake is simple: it's expensive. Attracting a new customer costs far more than keeping an old one happy. Not only that, but an old customer is far more likely to bring you new people via word of mouth than someone who isn't even a customer yet.
Which is why share of wallet makes so much more sense than share of market. How much does each of your existing customers buy from you? Do they count on you for all the things they buy in this market, or just some? Does Toyota sell me every car my family drives? Does Chubb get to insure every single thing I own? Usually not. Because marketers are so focused on more that they forget to take great care of what they've got.
Hugh Macleod, gifted cartoonist and profane marketing blogger is now making his living selling limited edition art work based on his cartoons. He's a brilliant marketer, of course, so he's not focused on more. He's focused on share of wallet. On selling his dedicated fans a remarkable souvenir that they can keep and display.
So, what's the problem? Share of wall. Unlike records or shoes, it's hard to buy a lot of art. Pretty soon, you've got no place left to put it, do you? Share of wallet turns into share of wall and you can't grow any more.
That's why you need to be realistic about how much share of wallet you can honestly expect, and why job one is delighting existing customers so much that they can't help but tell their friends. Preferably friends with very big houses.