The below tips work for most major search engines.

•  The more specific your search is, the more likely you
  will find what you want. Don't be afraid to tell a search
  engine exactly what you are looking for.

•  For example, if you want information about Windows 8
  bugs, search for "Windows 8 bugs," not just "Windows."
  Or even better, search for exactly what the problem is,
  for example. "I can't install a USB device in Windows 8." 
  You'll be surprised at how often this works.
  
  

•  Sometimes, you want to make sure that a search engine
  finds pages that have all the words you enter, not just
  some of them. The + symbol lets you do this.

•  For example, imagine you want to find pages that have
  references to both lions and tigers on the same page.
  You could search this way: +lions +tigers.   Only pages that
  contain both words would appear in your results.

•  Here are some other examples:
       +windows +7 +bugs would find pages that have all
  three of the words on them. Helpful if you wanted to
  narrow down a search to Windows 7 bugs, rather than
  on Windows 7  in general.
       +star +trek +insurrection would get you pages about
  Star Trek that also specifically mention "Insurrection,"
  the title of a Star Trek film.

•  The + symbol is especially helpful when you do a
  search and then find yourself overwhelmed with
  information.  Imagine that you wanted to reserve a
  camping space in California's Yosemite National Park.
  You might start out simply searching with the word
  Yosemite.  If so, chances are, you'll probably get too
  many off-target results. Instead, try searching for all
  the words you want to appear, for example,
  +Yosemite +camping +reservations.
  
  

•  Sometimes, you want a search engine to find pages
  that have one word on them but not another word.
  The - symbol lets you do this.

•  For example, imagine you want information about lions
  but don't want to be overwhelmed by pages relating to
  tigers. You should search this way:  lions -tigers.  That tells
  the search engine to find pages that mention "lions" and
  then to remove any of them that also mention "tigers."

•  Similarly, perhaps you are looking for information
  specifically about Windows 8 but keep getting pages
  about Windows 7 or Windows XP. You could eliminate
  them with a search like this:  windows -7 -XP

•  Perhaps you are a fan of the original Star Trek series
  but instead keep finding pages about Voyager, Deep Space
  Nine or Star Trek: The Next Generation. Try a search like
  this:  star trek -voyager -deep -space -nine -next -generation

•  In general, the - symbol is helpful for focusing results
  when you get too many that are unrelated to your topic.
  Simply begin subtracting terms you know are not of
  interest, and you should get better results.
  
  

•  Now that you know how to add and subtract terms,
  we can move on to multiplication. As in normal math,
  multiplying terms through a "phrase search" can be a
  much better way to get the answers you are looking for.

•  For example, remember above when we wanted pages
  about reserving a campsite in Yosemite? We entered all the
  terms like this: +Yosemite +camping +reservations

•  That brings back pages that have all those words on
  them, but there's no guarantee that the words may
  necessarily be near each other. You could get a page that
  mentions Yosemite in the opening paragraph but then
  later talks about getting camping reservations in the
  Grand Canyon. All the words you added together would
  appear on this page, but it still might not be what you are
  looking for.

•  Doing a phrase search avoids this problem. This is where
  you tell a search engine to give you pages where the terms
  appear in exactly the order you specify. You do this by
  putting quotation marks around the phrase, like this:
  "Yosemite camping reservations"

•  Now, only pages that have all the words and in the exact
  order shown above will be listed. The answers should be
  much more on target than with simple addition.

•  Likewise, remember this addition example?
  +windows +XP +bugs.  As you can imagine, multiplying the
  terms together within a phrase search would work better,
  because that exact phrase probably appears on good pages
  dealing with Windows 98 bugs. 
  So try this: "windows 98 bugs".

•  Remember the search for information about the latest
  Star Trek movie? We could transform that into a phrase
  search like this: " Star Trek Insurrection".
  But the movie's title actually has a colon after the
  word "trek," and many pages might also follow this format.
  Thus, a better phrase search might be:
  "Star Trek: Insurrection"
   

•  Once you've mastered adding, subtracting and
  multiplying, you can combine symbols to easily create
  targeted searches.  For example, remember the person
  who wanted pages only about Star Trek's original series?
   

•  We searched this way:
  star trek -voyager -deep -space -nine -next -generation.  
  A better search might use subtraction and multiplication:
  "star trek" -voyager -"deep space nine" -"next generation"