One of the things I enjoy most as President of the New York Stock Exchange (NYSE) is networking with our community of listed companies. Even more so, I enjoy having a view into the networking skills of the world’s greatest executives. A few months ago, the CEO of a global technology company and the CEO of an automobile manufacturer had a chance encounter on the floor of the NYSE. It should come as no surprise what happened next: these two captains-of-industry took time out of their busy schedules to spend time with one another, compliment one another on their recent successes, and suggest a future meeting to stay in touch. I see this scenario in action every day at the NYSE and I am convinced that this type of networking is crucial to succeeding as an individual, thrive in your industry, and have fun in your career.

When I think about my own career, I owe every job I’ve ever had to networking. In fact, my current role is the end result of a relationship that began with a business meeting in suburban Atlanta in 2001 with the current Chairman of the NYSE, Jeff Sprecher. When I walked out of that meeting in 2001, I made a conscious decision to find reasons and ways to stay in touch with Jeff. At the time, Jeff was the founder and CEO of a fledgling commodity-trading marketplace and there wasn’t necessarily an obvious benefit that I would receive from continuing my relationship with him; however, networking is about collecting relationships with interesting or influential people irrespective of the immediate benefit of these relationships. As it would happen, five years later, Jeff’s no-longer-fledgling business acquired the New York Board of Trade and he asked me to serve as President of this newly acquired business. Seven years after that, Jeff asked me to lead the New York Stock Exchange. If I had not spent five years after that first Atlanta meeting staying in touch with Jeff, through emails and phone calls, there is no way he would have considered me for president.

I would by no means describe myself as an expert on networking, but there are four key principles that I have used throughout my career to build powerful networks and maintain instrumental relationships:

Don’t limit your network
It doesn’t matter if someone is inside or outside of your industry, if they are interesting and influential, be willing to commit time and/or resources to meet, connect or help that individual. The most successful people that I’ve met at the NYSE – including Chairmen, CEOs, and Heads of State – have the broadest and most interesting range of networks spanning industries, occupations, geographies and ideologies. Sometimes it’s individuals completely outside your immediate sphere that end up being a connector or offering the savvy advice that propels you forward at a crucial junction.

Do your homework
Once you’ve secured a meeting, phone call, or introduction to network with someone – don’t mess it up! My personal rule-of-thumb: be prepared with at least two areas of common interest. For instance, before I met with Prime Minister Abbott of Australia, I discovered that he is a fitness fanatic and closely follows Olympic swimming. This unique information helped me break the ice by inviting him to train with me and a few friends – including a close friend of mine who swam for Australia’s Olympic team. After the small talk, the rest of the meeting went smoothly and we did indeed hit the gym the next morning (and, as an aside, the PM can do an impressive 10 pull-ups unassisted).

Don’t ask for anything in return
Networking is not transactional, but too often it’s approached in such a way. Play the long game and build the network for the sake of building the network. Early in my career, I offered to review a peer’s business plan without any expectations about a job, compensation or even a cup of coffee in return. This encounter eventually landed me the position of CFO for this well-funded technology startup.

Aim high
Often times people miss opportunities to network because they feel intimidated, particularly if the other person is more senior. However, there is very little downside when aiming high, other than a bruised ego from time-to-time. The worst that can happen is they say “no” or ignore you. At that point, it is onward and upward!

Tom is attending Fortune’s Brainstorm Tech conference from July 13-15 and speaking on the Enterprise Transformation panel.