The wait is over. Amazon has officially announced that the locations of its hotly-anticipated second headquarters will be Long Island City, New York, and Arlington, Virginia. The expansion is set to usher in a new era of growth at the tech giant as it seeks to expand its workforce by almost 10 percent. Amazon has said it will invest more than $5 billion over almost two decades to expand its 613,000-strong workforce by 50,000. That build-out will offer opportunities aplenty for the tens of thousands of techies who dream of working at the e-commerce behemoth. But with the new roles offering average salaries of $150,000, and the typical Amazon job posting receiving thousands of applications, competition is set to be fierce. So, it's important to figure out how you can get ahead of the crowd. One person who understands that better than most is Sandi Lin. Between 2011 and 2013, she conducted thousands of interviews at the company's Seattle HQ in her role as an Amazon "bar raiser." The position, which is held in addition to an employee's regular role, is designed to make sure every new hire raise the talent bar across the company, while ensuring a fair final decision-making process. The idea is that they can provide a layer of objectivity to the hiring process in departments outside of their own, Amazon confirmed to CNBC Make It. "It's sort of like a secret society," said Lin, noting that employees can express an interest in the role, but typically they're "tapped" for it. Usually only half of the employees who join the three-month program make it through to become an official bar raiser. But, for those who do, it provides a unique insight into the Amazon interview process, as Lin explained to CNBC Make It. That process can be broken down into four main steps:

1. Study the leadership principles

First up, Amazon interview candidates are expected to know the company's 14 leadership principles inside out and be able to demonstrate how they embody those values, said Lin. A typical Amazon candidate can expect to meet four or five interviewers, and each will be assigned a principle to look out for, she noted. She recommended going into the process with five stories that exemplify how you have shown those qualities in the past. "Walk in with these examples clearly mapped out in your mind," said Lin, noting that "customer obsession" is almost a guaranteed topic. "Bonus points for using the STAR method by describing the situation, task, action and results."

2. Highlight your input

Next, when describing those examples, or demonstrating the projects you have completed in the past, it's important to emphasize your specific contribution, Lin explained. "It's very common for people to start with a 'we' answer," she said. But while that's useful for adding context, interviewers are interested in your work and you should use the opportunity to sell yourself. "Some candidates worry about 'taking credit' individually," Lin noted. "However, this is actually critical to delineate the specific skills and behaviors you exhibited in the overall project, irrespective of whether or not the project that you're describing was a success."

3. Demonstrate curiosity

In the same way that Amazon wants people to raise the bar at the interview stage, it's also looking for staff who will raise the bar in the company, both in their immediate role and longer-term. As such, candidates shouldn't be afraid to show curiosity and demonstrate their ambition to learn and grow in the role, said Lin. "I liked it when candidates spoke about their excitement for the company and asked, in a diplomatic way, about how people can progress through the company while also showing commitment to the role in question," said Lin. That could mean asking questions like: "What would it take to go from a junior to senior engineer at Amazon?" Lin suggested. "Showing that curiosity is really awesome."

4. Ask thoughtful questions

That curiosity should also extend to the other questions you will be expected to ask during your interview, Lin explained. Lin recommended avoiding generic questions such as "why did you join Amazon?" and "what is it like to work here?" Instead, she suggested, take time to research each interviewer and come up with creative, thought-provoking questions. "Nothing is more impressive than candidates who come with insightful prepared questions that are tailored to each of the interviewers," she said. "It shows preparation, engagement, thoughtfulness, and genuine interest in the position and company."

Amazon CEO Jeff Bezos The Washington Post | Getty Images