I’ve heard a lot of different theories about how things get done. I’m interested in this topic, so I pay attention and see how the theories hold up.

Here’s the best one: a combination of focus and personal connections. Charlie Rose said this to Paul Graham, who told it to me.

It seems very accurate. There are lots of good things that I keep meaning to do but never quite make it to the top of my list; I never make any real progress at all on those. Conversely, I find that whatever I focus on most nearly always happens. Small-ish startups seem to be able to do about three things at once, and usually they are whatever the CEO is focusing on. Certainly anything that is not someone’s number one or two priority is unlikely to get done in the hectic world of a startup.

Most early-stage startup founders do a bad job of getting the company to focus on just two or three critical priorities—they chase whatever shiny new object appears that day. This is somewhat expected—the sort of people that start companies generally like doing new things, not executing relentlessly on the same things. But restraint is critical. It’s very easy to justify taking on one more project by saying that it won’t be that time consuming. Unfortunately, it will likely either be time consuming, or it won’t be worth anything. Most founders know what to do; they just don’t know what not to do.

The Y Combinator version of focus is “write code and talk to users”. For a startup that is just a few people, most other things are a waste of time (assuming the founders have already thought through the strategy of the company, and that “talking to users” also implies getting users). For whatever reasons, many founders love to spend time on anything else—worrying about the details of corporate structures, interviewing lawyers, doing a really good job bookkeeping, etc. All of this pretending-to-run-a-company gets in the way of actually running a company. The best startups we fund come to office hours to talk about their product, how to evolve it, how to grow faster, and excited to show us new features their users want. The worst come to talk—again and again—about everything else.

On the personal relationships part, most people eventually realize it’s hard to do really good things by yourself—most of them just require too much work. Successful startups usually find that their biggest problem is hiring, and certainly hiring well is the highest-impact thing a founder can do for his startup (and the best thing an investor can do is fund great founders). “Always be recruiting and promoting talented people” is very good advice. Having good relationships with the people you work with is also very good advice.

I make it a point to meet and help as many smart people as I can; besides being fun and interesting, this is important to getting things done. These are the people I tend to try hire or fund, and I think it’s the same for lots of others. This is not really nepotism; I think working with your friends is a good strategy, and smart, effective people tend to like other smart, effective people. The best hires I’ve made or seen other companies make are usually friends or friends of friends. Partnerships and sales also rely heavily on personal relationships, for many of the same reasons.

It’s easy to not spend enough time on personal relationships—it seems in conflict with focus. But it’s an important exception. It’s also one of the most enjoyable parts of work.

When you combine extreme focus and great teams, magic happens.