Choose research participants carefully. Don’t just target potential users for feedback – ask extremes of the user population too, as this is where the really useful ‘workarounds’ can appear. Frequently, the things that happen in an extreme situation will also be of great benefit to the majority of users.
Don’t just rely on friends or colleagues, either. A recurring issue is that designers tend to talk to each other a lot. The result is often a tiny minority designing for a tiny minority.
And remember that user research is highly unpredictable. People can be tricky to deal with; they change their minds and can be highly idiosyncratic in their behavior. Beware of assuming these are “cookie-cutter” findings that you can simply cut and paste into other, similar projects – this won’t work.