I've mentioned before (In fact, I checked, and it was in my very first networking note) that there are two types of people you should be aiming to network with:
Those you can help.
Those who can help you.
The group of those you can help includes potential customers and other business people to whom you can make referrals. I want to focus here on identifying members of that second group. The contact sphere for you is the group of people who serve your customers but do not provide your product or service.
More specifically, your contact sphere is the group who has your customers but is not in competition with you.
Obviously, growing strong networking relationships with these people is a great way to grow your career support connections. They can refer you to their peers or colleagues, you can easily reciprocate, and you don't have to worry about competing with them.
The challenge here is determining which connections best fit into your particular contact sphere. If you are a financial planner, estate planning attorneys might be good to have in your contact sphere, but so might family law attorneys. It would depend on whether your focus is on financial planning for retirees, or the special needs of people going through a divorce. So the ideal contact sphere depends, at least in part, on where you focus your work.
Contact Sphere Creativity
There are some natural, obvious contact sphere groupings. Tradespeople would include other trades in their contact spheres, as well as realtors. Health professionals would include diet and exercise people in their contact spheres as well as different health disciplines. Technology professionals would include business services and organizations that support their clientele in their contact spheres.
Your competition might also be included in your sphere, especially if they serve markets you do not wish to serve. For example, a realtor will often want connections in regions they do not sell because a person may be moving there and they can often share commissions by making a referral. Or a technology consulting firm wants to handle clients in an office setting and are not interested in the home users.
The real fun (and the greatest value) comes from specifying an ideal employer, getting to understand their specific issues, and growing a custom contact sphere to solve their particular problems. If you know that your best clients are estate planning attorneys in small firms of under ten lawyers who focus on parents with children with special needs, you can develop a contact sphere of IT people, health an home-care professionals, tradespeople, and others who support your specific ideal client. You (and your team) will become the leader in that market.