This entrepreneur worked for 2 companies acquired by Amazon—here are his top 4 tips for getting ahead

Christopher Tung graduated with an English degree in 2011 and moved out to New York City, bringing little besides the $3,000 he had saved and his determination to make it. He didn't have a job, and the one interview he had planned fell through.

After more than two months of rejection, he was down to his last $1,000, and his luck turned. He was acquired by the small e-commerce company Quidsi, which was itself acquired by Amazon. Six years later, he has held five positions, including two at different start-ups absorbed into Amazon, and one at Imgur.

Along the way, he learned how to how to keep his ear to the ground, a skill Tung says has helped him navigate his career and figure out when it's time to move on to the next opportunity.

"You never want to be the last one to go," he tells CNBC. "Move when it's advantageous."

Tung co-founded the career start-up Huttle with his former Imgur peer, Michelle Linn. It helps millennials find new opportunities in part by offering real-time career mentoring and advice from professionals at companies like Amazon, Facebook and LinkedIn.

Here are Tung's top tips for identifying when it's time for a change and how to discover what's next.

1. Grow

"I'm a believer [that] you should learn," Tung says. "If you stay at a company too long, you could limit what you could learn."

The opportunity for learning and growth is the reason Tung worked for five companies in six years and it's also what he believes separates professionals in the millennial generation from the rest: their willingness to move on.

To grow, it's not always necessary to change companies, he says. If you're getting new roles or moving up within your organization, that makes room for growth too. In general, he advises seeking new responsibilities when you feel you feel stagnant in your current position.

2. Ask

One of the reasons Tung decided to build a company that offers job opportunities and forums is to encourage advice-seeking and sharing. He credits his ability to make responsible professional decisions to mentoring he received from his bosses and peers.

"We need to be more comfortable asking for help," he says. "A lot of people think they will hear, 'No.'"

But if you hear "No," what's the worst that can happen? Tung says there is not much to lose and only something to gain. At the very least, you can establish a connection.

3. Adapt

"The definition of insanity is doing the same thing over and over again," Tung says.

Yet that is the mistake he's seen some young professionals make. When people apply to dozens of jobs with the exact same resume and they don't get calls back, it might be because they are not trying something new.

Instead, Tung suggests making different iterations of your resume for different job positions. Experiment with order and the message you convey to have a better shot at getting a call for the interview.

4. "Just do it"

It's not only Nike's tagline: "Just do it" is also a meme that alludes to Shia LaBeouf's brief but effective viral motivational speech. Linn and Tung both became very familiar with it during their time at Imgur, and they found that there's a practical takeaway from the catchphrase.

"We often find ourselves in positions where you just stay the course," Tung says.

He recalls considering the option to just stay at Quidsi, but had he not made a move, he says he would have missed out on several opportunities. He wouldn't have been able to work for yet another company acquired by Amazon, or met the person who would help him launch the start-up.

More often than not, he says, it's rewarding to chase what's next.