Let’s say that you enter a query into your favorite search engine, and you don’t see anything remotely relevant in the first page of results. What do you usually do next?
a) Click through to the next page of results
b) Try a different search engine
c) Give up
d) Try something else entirely
(See Poll #2 (aka lame-all-the-same) and Poll #1 (aka heinous pornspam).)
Tim Converse 
I try another search with more specific terms. A search for [BBQ San Francisco] might not give me what I want, so I will search again for [BBQ restaurant “San Francisco”] to try and hone in on the best BBQ joints in the city.
I reformulate my query. Then if that still fails I go to a different engine.
it depends, but I just generally reformulate the query.
Sorry, i should have included reformulation explicitly, rather than under the “something else”.