Niklas Zennström, the co-founder of Skype, who is now an investor in international growth-stage companies, hails from a suburb of Stockholm, Sweden.

Growing up in a small country may have had no small effect on his outlook on international growth, Zennström said at the TechCrunch Disrupt conference in New York City on Wednesday.

"First of all, I'm coming from a small country, Sweden, with 9 million people," he said. "That has meant for me, if you are successful at your home, you are not even successful."

In building Skype, beginning in 2002, Zennström and his co-founder, Janus Friis, always had their sights set on international growth. And today--after the pair sold Skype for $3.1 billion before reacquiring it and again selling it, this time to Microsoft for $8.5 billion--that mindset is part of the playbook at Zennström's investment firm, Atomico.

He said he's tapped some former Skype employees around the globe to help build infrastructure for Atomico, which has offices in London, Beijing, São Paulo, Istanbul, Tokyo and Seoul, and which has invested in four dozen companies across four continents. And that has given the fund an advantage. 

"We have been in these markets for a long time," he says. "Those are deep networks and relationships. Specifically in these markets, having these country managers in these markets is something we've built up over years."

But not every investment Atomico has made has led to spectacular international launches. For example: Fab.com's lackluster European launch, which was followed before long by a dramatic downsizing

"Sometimes we've been too eager to help companies expand internationally when they're not ready," Zennström said. There are a couple of pitfalls to avoid. For example, don't jump the gun--and don't simply expand because your competition is doing so.

"Sometimes you do it because you're too eager, or sometimes you do it because there's too much competition," he said. "It's very hard to get the timing right."