We go along to their meetings, where members talk for one minute about their business, and what kind of companies they want to make contact with.
But of course, you can't attend every networking event if you did, you'd never do any work. but I think you'll find that most people prefer lunchtime as it's more convenient and you'll probably meet more people. However, as to what makes a good meeting, well an effective networking meeting needs to have a clear agenda. It's also useful if handouts with company profiles are circulated to everyone beforehand. Of course, meetings aren't the only way of networking.