One of the biggest mistakes people consistently make in the networking process when seeking new jobs... is they ask for jobs!
"What! Isn't that the point of networking??? To find a job???"
Yes ...and no!
I consistently have people approach me asking if I know of job in their field, and I hear them ask the same question of most others they meet as well. I'm a recruiter, and I do know of open jobs. However, not usually the kind of jobs they are looking for, and most people don't know of open jobs... even at their own companies. They are busy with their own jobs, and families, and other interests and have no reason to ask or pay attention to what jobs are open at any given time.
So, while they sincerely would like to help... when they're asked if they know of an open job, nothing comes to mind and they feel badly they aren't a better resource for you. The conversation becomes quiet, and awkward, and they walk away feeling useless, and you walk away feeling like this networking thing is a waste of time.
When you don't ask for anything in your networking conversations, the conversations seem to end in the same way. The contact may even say something like...
"I'll certainly let you know if I hear of anything!"
Which may sound encouraging, however, almost never produces any results. Typically, it's because they are thinking the same question you decided not to ask: "Do you know of any jobs in my field?"
The key in job search networking is to help them change their thinking, and look for worthwhile contacts for you that get you one step closer to an opportunity rather than the job itself.
If you're an Accountant, networking with the stay-at-home mom next door, having her think of her cousin that is also an Accountant gets you a valuable contact that is more likely to know of Accountants, or Accounting Managers at companies you may like to pursue. If you're brother-in-law is a sales person that might sell to companies that you have an interest in, the Purchasing Manager he calls on is likely to know who an Accounting Manager in his organization might be.
Realizing that the goal in effective job search networking is to get names of other people that may help you get closer to the right opening will help change the conversations and become far more productive. While someone is highly unlikely to know of an appropriate position for you... it's highly likely that they know someone that gets you closer to someone that does know of an appropriate role.
People overwhelmingly want to help in some way... they just often don't know how. As soon as they realize that you are looking for a job, they will certainly tell you if they know of one. They want to help, and that's the obvious question that comes to mind. It doesn't usually occur to them, however, that a name can be a tremendous resource for you.
Make it a point, in your job search networking, never to ask if they know of an open job, and see your results improve.