Funk-rock music greets all shoppers who enter Island Trading Co. on Oak Bluffs avenue, where beach hats and colorful baseball caps cover the walls in a neatly-ordered grid. There, a fedora-clad man with loose gray curls, glasses and bristly white facial hair greets you from behind the counter.

If you are in the market for a hat, owner Jim (Brooksie) Brooks doesn’t stay behind the counter for long.

“I’m a belly to belly, eye to eye salesman — in other words a dying breed of salesman,” said Mr. Brooks, during a recent interview at his store, where he reflected on his many decades in Island retail. “I’ve been doing this for 48 years, and the whole trick is that every year is different.”

Now 78, Mr. Brooks has lost none of the energy that has enabled him to sell hats and attract returning customers over the years.

“I’ve got a killer following,” he said. “About seven out of every ten people that I sell to I know from the past.”

A hat for every outing. — Ray Ewing

But Mr. Brooks wasn’t always a hat seller. He opened his shop as a T-shirt outlet back in the '70s.

“After one year, I was the only T-shirt person in town. But after five years, there were 10 people” he said.

And so, sensing the market would soon become oversaturated, Mr. Brooks decided to pivot to the hat and sunglasses business, with which he had little familiarity. Quoting famed trumpeter Dizzy Gillespie, he said: “You often do your best work when you didn’t know what you were that’s what happened to me. I invented my life in the hat business.”

Before starting his shop in Oak Bluffs, Mr. Brooks got a crash course in salesmanship on the mainland. After serving a stint in the Air Force and getting a marketing degree in college, he went on to work for a wholesale hairdressing supply business in Brookline.

“It’s an obnoxious business,” he said, which mostly consisted of him selling wigs. The silver lining of the experience, though, was getting to work under master salesman Robert Greenberg, who went on to become the founder and chief executive officer of Skechers.

“That man taught me, for this little store in Oak Bluffs, the principles of selling,” he said. The main pillar of salesmanship, he recalled, is to never lie to the customer.

“Set daily goals and never tell a story. It is that simple,” he said.

Those fundamentals, Mr. Brooks said, paired perfectly with his natural conservation skills.

“I have this reasonably-uncanny capability to fire from the hip, and I have a sense of being a hat whisperer,” he said.

But a salesman is only as good as his inventory, and it has taken Mr. Brooks decades of mistakes in hat sourcing to develop his stock. In picking out a selection that will appeal to Island summer visitors, he focuses on three fundamentals: SPF coverage, affordability and packability.

Ever the salesman, Jim Brooks knows what you need. — Ray Ewing

When a customer comes in, Mr. Brooks said he sizes up their needs and then the show begins. His sales style is fast paced — filled with motion, enthusiasm and profanity.

“Salesmanship means that I’m a good presenter,” he said. “I’m presenting you with a good opportunity to be a good buyer.... I’m passing the baton to you.”

Mr. Brooks also benefits from the tight-knit community of “benevolent competitor” store owners across the street on Circuit avenue, estimating that around two customers come as referrals to “Brooksie’s place” from other stores on an average summer day.

Though Mr. Brooks is now nearing the age of retirement, he says he is determined to make it to the shop’s 50th anniversary, which will coincide with his 80th birthday.

“I definitely feel energized,” he said. “This is the perfect business for me, because I’m kind of crazy.”