Forget becoming a trusted adviser. Customers want a manager not a consultant.
For decades, sales pundits have been advising companies to practice a "consultative" style of selling. It was bad advice then and it's bad advice now.
The idea behind consultative selling is simple. Rather than acting like a salesperson (i.e. making sales pitches), you strive to become the customer's "trusted adviser," just like a management consultant who's hired to help solve problems.
While this sounds smart in theory, in practice it's dumb because no customer really wants an "adviser" or a "consultant." Customers want somebody who will take responsibility for a crucial part of their business, not some smart**s who kibbitzes from the sidelines.
Consider: everything a company buys from another company, it could decide to do itself. Apple, for instance, could decide to make its own screens, or mine its own minerals to make the metal cases of iPhones and iPads. It doesn't though. Instead, other companies sell those items to Apple.
The same is true with smaller firms. Suppose you're selling a service that helps small software firms support their products. Those customers could decide to build their own service centers, but instead they decided to let you own that essential part of their business.
Customers want YOU--as the representative of your firm--to be personally responsible for making certain that a crucial job gets done. In other words, rather than a consultant or an adviser, the customer wants you to be a manager.
That's an important distinction. The ultimate source of your credibility is never your ability to provide sage advice, but your ability to deliver, to solve problems, to take on the hassles that the customer would rather not think about nor bother with.
In order to sell to a business, then, you must convince the customer that you're the type of person whom they would normally hire to manage the function that your firm provides, had they decided to keep that function in-house. This means you must:
Have a thorough knowledge of that function
Understand how that function fits into the customer's business
Be capable of ensuring that the function achieves the customer's goals
Be able to manage the team that will provide that function (i.e. your firm)
Look, walk, talk and act like the managers inside the customer's firm
Be willing to put the customer's interest first--just like an internal manager would
In other words, if all you have to offer when you sell is "consultative," you might as well not bother.