Networking is ideal for those of you who are starting out in business, with no existing clients and a limited budget. The investment is more of time than of money.
There are plenty of opportunities for networking, both formal and informal. Join various groups and organizations, including chamber of commerce networking meetings and industry groups.
I read a very interesting definition of a customer. It said that "a customer is someone with whom you have business dealings". In a networking group, this means that all the other members of the group are your customers. The business dealings you have with them involve the exchange of leads and referrals.
Generally, you have to sow before you can reap. That is bring leads and support into a group before you expect to receive anything in return. Bring more leads than you expect to receive in return, and figure on a ratio of about ten to one. You may do much better than that, but if you go in prepared to give more than you receive, you will fare better.
You should try to give good customer service to the other members in the group, since they are your customers. Treat them with respect. Show genuine interest in them and their businesses. Follow up outside of networking meetings. Respect also means not going after other members like you are a predator and they are prey. I call this last approach "Trawling" like a deep sea trawler that cares little about the life on the ocean floor. If you mess up the group that can help you find leads, then you will soon be out of luck.
Any lead you get from the group could turn into your biggest customer ever. You don't know who might bring the lead, so you had better treat everyone in the group to your very best service.