It is truly amazing to me that some of the most successful startup CEOs seem to have poor people skills.

For example, if there is any truth to the portrayal of him in 2010?s The Social Network, Facebook CEO Mark Zuckerberg is not a great people person.

But surely he has developed important relationships -- most likely with Sheryl Sandberg whom Zuckerberg believes excels at all the parts of the business that he wants to avoid, with the investors who gave Facebook the capital needed to grow, and with technical people who improve and extend its services.

For advice on how to build relationships, I interviewed Lars Albright, CEO of Boston-based mobile marketing services provider SessionM -- a roughly 100-person startup that raised $12 million in May and is on track to hit $100 million in revenue over the next few years.

Before that, he cofounded two companies that were sold for a total of $550 million to Apple and VeriSign.

Here are his four keys to building successful business relationships.

1. Be likeable

There is no way to predict whether you will click with another person but you must do that if you want to get a relationship off to a good start.

Said Albright, "When you are CEO of a startup you have to be open to meeting a lot of different people. They should enjoy you as a person because you are compelling, you listen intently, and ask thoughtful questions."

2. Be persistent

If you are trying to turn a big name company into a customer, there is a good chance that you will not be able to email its CEO and get a meeting.

Instead, you will likely have to use all of your networking skills to get an introduction to someone who might be able to introduce you to someone who can get you entre into that CEO's office.

"There is the persistence factor. There are times when you have to go after getting in touch. You will have to send multiple reminders. And if you do get a meeting you have to build on small kernels," said Albright.

3. Be trustworthy

It has often been said that a reputation takes a very long time to build and can be destroyed in an instant.

As I wrote in Value Leadership, the key to building up a reputation is to fulfill your commitments. That means both telling someone what you plan to do and then doing it.

Each time you fulfill your commitment, you build up your reputation and that leads to a higher level of trust.

When you have built up enough trust, you may be in a position to forge a longer-term relationship -- whether it's with a cofounder, employee, investor, customer, or partner.

As Albright said, "You have to have credibility so people believe that you will do what you say."

4. Forge a genuine connection

Doing these three things can help you get a relationship started but it won't last without a genuine connection. Beyond clicking at a personal level, that means that you build a relationship that makes both parties better off over the long-run.

Explained Albright, "You have to build different relationships at different stages of a startup's growth. These include cofounders, early team-members, investors, partners, and customers. They have to want a two-way relationship that is more than just the short-term ask."

If you can't follow these principles, hire someone who can. Those relationships are critical to achieving your ambitions.