For some crazy reason contractors have a bad habit of networking with the wrong people. You need to go to where your clients are. Let's use a fishing analogy. The first key to catching fish is fishing where the fish are. If you happen to choose a pond that doesn't have fish, you will wear yourself out trying to catch the fish that aren't there. The same goes with networking.
So where might they be? The first answer should be obvious - professional associations. Not yours. Theirs. If you are a trade contractor who works through general contractors you should attend your local Association of General Contractors monthly meetings and events. If you are a non-union contractor, consider attending Association of Builders and Contractors events. Those two groups were layups. Let's take this to the next level.
Maybe you should be networking where your clients are networking. In other words, go to events held by your clients' clients. You'll benefit in two ways. You'll most likely find a better cut of clients there as clients who understand marketing and sales are almost universally better tuned to value added services. They are less likely to be rigid on low-price-always-wins.
So where are your clients' clients hanging out?
If your niche is large commercial projects you are not likely to find building owners hanging out at professional meetings. They tend to hang out at charity functions and donating time to charity organizations. Charity organizations are a great place to network. You'll need to get involved. Highly successful people will wait to see your genuine commitment to their favorite cause before giving you an opportunity to do work for them. In the fifties and sixties business was typically conducted on the golf course. Not so much anymore. Today business relationships get built by working side by side in charity organizations.
If you are a general contractor or a service contractor who wants access to small commercial projects you have a handful of additional routes to explore for your networking. Existing building projects are typically let through a property management or facility management company. Those individuals often attend local International Facility Management Association meetings. They will also attend Building Owners and Managers Association meetings. Once again, you'll need to get involved with those organizations to make serious traction and get your name out.
If you focus on a specific client niche such as industrial, healthcare or pharmaceutical join the professional associations that serve those groups and, once again, get involved. You may run into a handful of competitors at the monthly gatherings, but there will be plenty of work for all of you.
Other groups to consider networking through are various architectural and engineering associations. The beauty of this approach is so few of your competitors will think to rub elbows with them. You will pretty much have the network to yourself.
A word about designers, accountants, insurance agents, bankers, attorneys and other professionals: don't expect them to recommend you to their clients. Heck, it would be a miracle if you could pry the name of a client from them. Professionals are paranoid about referring a service provider who might reflect poorly on the professional. I have rarely heard of a professional referring a contractor to one of their commercial clients. They will not hesitate to recommend a residential remodeler or service contractor to their family and friends, but they almost never refer a commercial contractor to one of their cherished clients.
Another possible network opportunity could be your church network. Depending on the town in which you live, you may already be a member of a highly networked religious organization. I happen to live in Kansas City where the Catholic Church remains strong. I've witnessed that network taking care of its own. Much business has been conducted amongst its members and their ties are strong to one another. You may have a similar opportunity among your church network.
Networking is hard work. It can take up quite a bit of time. Split the duties up. Make it a company policy that every member of your front office sales, operations and senior staff gets involved with one organization. A steady flow of leads is in everyone's best interest. Everyone should participate in networking.