A decade ago, Calvin Harris was stocking shelves at a supermarket in rainy Scotland. On Halloween weekend, the DJ and music producer was setting off fireworks on a private island off the coast of Puerto Rico. All part of his headlining set at Bacardi Triangle, the epic three-day music festival on a private island in the Bermuda Triangle hosted by the liquor company. His success as both a recording artist and touring act has made Harris a sure-bet for partners like Bacardi, Armani and the MGM Grand in Las Vegas.

Earlier this month, Harris hit a new career-high with the release of his fourth studio album. First week sales of Motion were more than double those of his previous release. The album's lead single, "Summer," is Spotify's most-streamed track of 2014 with over 200 million streams, earning Harris somewhere around $1.5 million. 

But music sales and streams make up only a fraction of the estimated $66 million the artist pulled in this year, according to Forbes, making him the top-earning DJ in the world for the second year in a row. 

During a rare break, Harris shared a few secrets behind his superstar success with Inc.

Be your own biggest fan

"You need to make sure that the music you are releasing is something you still like," Harris tells Inc. The DJ started his music career as a indie electro-pop singer-songwriter, beloved by the blogosphere for his quirky demeanor and upbeat '80s-inspired beats. His signature musical style has remained mostly intact, even as the production value in his live shows and music videos has skyrocketed.

"It's easy when you get a successful record to get swept away and [start] compromising ideas because you think maybe they will be more successful," he says.

Find the right muse

Harris' breakout as a global superstar came in 2012 after producing "We Found Love," a Rihanna collaboration that went directly to number one on the Billboard Hot 100 chart. The success of that song made him a highly-coveted producer in the pop world, but it was important for Harris to learn to say no.

"I've gone out of my way to not work with anyone I don't like," he says about musical collaborations. Since "We Found Love," the Grammy nominee has gone on to work with Gwen Stefani, Ellie Goulding and Florence Welch.

Ride the momentum

Just as electronic dance music was beginning to crossover and blow up into a $6.2 billion global industry, Harrris leveraged collaborating with pop's biggest acts to become a marquee headliner of his own. 

Music festivals, club gigs and live events alone brought in about $4.2 billion in 2013, and Harris didn't let this billion-dollar music phenomenon pass him by. He played 125 gigs that year, and demand for the hitmaker DJ with a pop appeal continues at an all-time high. According to the MGM Grand nightclub where he's a resident DJ, Harris could double his gig schedule at the club and still be a sell-out.

Create new ways to excite consumers

During the first six months of 2014, digital album sales in the U.S. fell by 14 percent, according to the Recording Industry Association of America. Music fans are spending less on buying music and more on attending live concerts and music festivals. This is where artists can create a new level of excitement for fans, says Harris.

"If you think back to CDs, it was the experience of buying the album and getting the artwork and reading the credits. Now it's all just files and everything is all over the Internet within the first hour of things being finished," Harris says. "Kids that just download, they are looking for that connection with the artist and that excitement is now coming from the live show."

Never take a night off

So far this year, Harris has headlined Coachella, Lollapalooza, Austin City Limits, the iTunes Festival, Electric Daisy Carnival, the iHeart Radio Festival and Bacardi Triangle. In between major music festivals, the DJ can be seen live in Las Vegas at a MGM Grand nightclub for his multi-year residency, which he was reportedly paid $10 million to extend for another year. 

Oh, and expect to see him in more tailored suits. The DJ just signed on as the new face of menswear brand Emporio Armani. Sure beats a supermarket apron.