Don't fall in love with your users.
I don't mean you can't develop romantic attachments to them if it's appropriate. What I mean is don't be so bowled over by what they have to tell you that you drop all your ideas and make exactly what they say.
When you first meet a user group and find out about the world they inhabit and some of the knowledge and tools they use, it can be easy to be swept up in it. This comes from their passion and commitment to their subject (you might seem the same if the tables were turned).
It's easy to then think, "My ideas are meaningless compared to what they're telling me." Think again! The best work will come from a mix of your ideas and their knowledge. You need to use them to inspire you and help you refine ideas, not rule you. You need to take what they say with a pinch of salt. It's easy to think, "But they know best, I'm not worthy," but you have to have confidence in yourself as a designer. I'm repeating myself, but that's because I've seen it happen so many times.
Rory Hamilton 2005 
I would always go to users with some kind of catalyst, either a sketch of a design for them, or some kind of probe technique (more on probes later). So you have a starting point, something to talk about, not just, "Tell me what you do?" If it's a design you should be clear it's a sketch and you would like to know whether it's something they'd like or does it make them think of something they would like. Even if they dismiss the idea they will usually come up with something to talk to you about.
Anecdotes are good, hard data is one thing (90% of Firefighters are men), but stories about real people's experiences in the real world can inspire you more than anything. Let them talk, let them ramble, be patient. Just don't think they know everything and you know nothing, have respect for yourself as a designer, don't fall in love...
