Every book, speaker, tape and website will tell you that the basis of networking is to "Give First!" If you think of networking as selling, "give first" means give them a brochure, product sample, or invitation to a sales presentation. That is a self-serving gift. Give first means to genuinely give of yourself, your time, or something else of value to the other person. It's something that they need, or appreciate, or can use for themselves.
What you give does not have to be expensive, valuable or even tangible. And sometimes even when you don't realize you are giving, someone else will take away something of value from what you did or said.
If you feel frustrated at the results of your networking, check your basic beliefs. If you think it's selling, you're going to feel like you require equal value for what you've given. Because selling is the exchange of goods and services for something else of value, right?
You'll leave events feeling taken advantage of or that the event was not worthwhile. And the people you meet will feel as if they were expected to take what you were selling when they didn't expect to be sold. Not a very satisfying feeling for anyone.