Yes, it's the mantra of the career coach pros out there, but does it really help? Well, it depends. If you are in the market for a full time job in your local area, then yes. If you are searching for SAP contracts then I think no. Let me explain.
If you are looking for a full time job in a specific geographical area, then absolutely join all of the appropriate organizations in that area. For example for a computing career join the local chapter of ACM (Association of Computing Machinists). At those meetings you will interact with potential contacts who may be able to hire you; refer you to another hiring company; or put you in touch with their contacts working at a desirable company. You may also interact with head hunters who are networking to find suitable candidates. These activities taking place in say Liverpool NY will be great for finding a job in Liverpool NY. However, it is unlikely to help you find a job in New York City. Pretty obvious eh?
If you are freelancing and looking to land a contract in a specific technology, say SAP, then I am not so sure networking helps. In the SAP world there is a rigid structure of client, recruiting company, consultant. It is extremely rare for a consultant to work directly with the end client. With that in mind, networking with end clients is a waste of time. They are not going to hire you directly. There is an organization called ASUG (America's SAP Users Group) in which I have been a member for 8 years. I have attended almost all of my regional chapter meetings and many chapter meetings throughout the US. What is the number of contracts landed as a result? You guessed it; 0.
More on this later.