There’s a joke about a guy crawling around on a sidewalk under a street lamp. Someone asks him what he’s doing, and he says he’s looking for his keys. A lady asks how’d you lose them, and the guy says “I tripped on the bridge and dropped them.” So, she asks, why are you looking for the keys over here under this street lamp? “because the light is better”.

Many people approach networking in the same way. They network with people who are easy to network with, instead of people who can actually provide value. They get together with the same group of former colleagues or references—even when they’re all so tightly connected that they don’t really provide unique access to one another.

A good network has weak ties, meaning not everyone in your network is a close friend with you and your other contacts. They come from different communities, and provide connections to a broad range of groups.

Ideally, you’ll have 7 kinds of people in your professional network:

1. (Current and former) Customers: These are people that have already bought from you. You should be strengthening these relationships, even when they’re inactive, because they may soon be in a situation to buy from you again—or serve as a source of referrals, or as a reference.

2. Prospects: There are likely many people who “could” someday be a customer, but aren’t today. Get to know them, so when they’re ready to buy, you’ll be top of the list and front of mind.

3. Mentors: Mentors are people you can learn from. Just because you may have completed your formal education doesn’t mean you’re done learning. Seek out people who are ahead of you in their career, or who have expertise you seek to develop, and build a connection.

4. Peers: Remember how important it was in high school to have study buddies in every class—someone who shared notes, helped you out when things got tough and kept you laughing? You still need people like that—these are people at about your level, in similar roles to yours, both inside and outside your organization. You can bounce ideas off them, ask them questions too mundane for mentors and compare notes.

5. Referral sources (upstream): Some people will never be in a position to hire you, but know lots of prospective clients and have good relationships with them. Often they are upstream—meaning a customer buys from them before they would buy from you. For example, if you’re a decorator, it might be helpful to have architects and realtors as referral sources.

6. Support sources (downstream): You will look better if you can anticipate future needs of your client and have the connections to help them. Decorators need to be able to recommend painters, carpet installers and handymen.

7. Mentees: It’s more than good karma that justifies finding people coming up in their careers behind you. Mentees force you to explain your logic and how you do things, which often helps you clarify your own strategy. You might be surprised by what you learn from them, since they are establishing their approach in a different time. And finally, people you mentor might be good hires one day.

And remember: Loose-ties are the key to a strong network. Go beyond your close colleagues and invest in maintaining relationships with more casual contacts. If you focus your relationships too narrowly, you’ll end up with a group of people who all have the same connections. By building ties across a broader community, you increase your reach, your sources for information and ultimately, your personal brand.