'Suicide Squad' Star and Rocker Jared Leto's Top Tip for Startup Founders 'In a band ... it's very similar to a startup. You're a few people in a garage,' he said.

The key to successfully multitasking? "Get really good at saying no."

That's the message from Jared Leto, Academy Award-winning actor, rock star and successful tech investor.

"You have to be really good with your time. You have to be incredibly focused on what's important, what the priorities are," Leto told CNBC's Squawk Box in an interview Tuesday.

"In a band ... it's very similar to a startup. You're a few people in a garage," he said, recalling the early days of Thirty Seconds to Mars.

Leto learned to "play a lot of roles" with his band, not only as singer-songwriter but also as marketer and social media advocate.

"It put me on the path early on to be independent and entrepreneurial. And it lead me to the tech world," he said, adding tech investing was something he started to do quietly 10 years ago.

Leto has made more than 50 investments in early stage tech companies, including ride-hailing service Uber and home rental marketplace Airbnb. He serves as an advisor to several startups. He also founded a handful of small companies.

"I would say almost every investment I made I've been incredibly proactive, really aggressive," he said.

He was also an investor in smart home startup Nest, which Google purchased in 2014 for $3.2 billion and now resides under the Alphabet umbrella.

Even with such an impressive stable, there were companies that got away.

Leto recalled being too late to put money into the virtual reality startup Oculus, which sold to Facebook in 2014 for $2 billion. He also said he met with Instagram just days before Facebook announced its $1 billion acquisition of the photo-sharing site in 2012. "They were looking around and giggling. And I said, 'What's so funny?'"

They might not have laughed if they saw Leto's take on the Joker in the upcoming supervillain movie "Suicide Squad."

^{Source: Warner Bros.}

Leto said he perfected his Joker's maniacal laugh walking around the streets of New York City and Toronto. "I would kind of … see what laugh would would get under people's skin."