In our research, every time we found a site where the search results were doing what they should, we also found a team that had worked really hard to make it that way.
Those teams all have something in common. They’ve experimented thoroughly, trying out dozens of designs and repeatedly watching users. They’ve frequently scoured their search log data, studying the terms users employ and comparing them to the results the site generated.
They’ve ended up with great search result pages, but it has taken months (and in some cases, years) of constant studying to get to this point. There is no way, as far as we know, that you can produce a great search results page without spending the time and effort to build it.
Jared M. Spool, Producing Great Search Results: Harder than It Looks, Part 1