The benefits of networking are huge. There is no better return on investment than a face to face meeting and exchange of information. You may give your card to someone that does not need your services, but they may meeting someone that does. They will then forward your card/info.
Networking does not mean you have to sign up with a group, although it does help. Networking is keeping your eyes and ears open to whats going on around you and meeting as many people as you can. Think the girl at the cash register is just a cashier? Well, she might be in college right now and will need your services in the future or she might have a boyfriend that owns a sign company. Keep your mind and ears open. And connect others when you see a fit. They will return the favor.