You can use double quotes to search an exact phrase. George Carlin has a great bit about losing things, and one of the things he mentions is frozen banana guacamole. If you want to make sure you get all those words in that order, use quotes: “Frozen banana guacamole”
In the image below, you can see the difference in the search results with and without the quotes. They're quite different.
That's a dramatic difference in numbers of results.
You can also use the minus sign to exclude results. For instance, I really like Star Trek, but I was never much of a fan of Voyager. If I want to do a search for Star Trek that doesn't include any results with Voyager, I can use the minus sign to keep those results out.
star trek -voyager
R.I.P. Arlene Martel
Another powerful tool is the site: operator (without a space) to limit results to one particular domain. I want to find out how often this very site uses a particular word, for example:
Site:macobserver.com amazerbeams
One result. Clearly I need to work this word in more often!
And of course you can combine all of these in interesting ways. I want to search Wookieepedia for movies, but only ones that don't feature Teddy Bears in Space™:
site:starwars.wikia.com movies -ewoks
It's much nicer without him. Trust me.
Google has removed the common “+” operator as a search expression since that company wants to use it over at Google Plus, but for those who are hardwired for boolean expressions the plus sign works at Bing, DuckDuckGo, and Yahoo! to include specifics in your search.
Each search engine has tailored some of its commands to complement that site's offerings; what works in one place may not work in others. You can check the help pages for Google, Yahoo!, and DuckDuckGo for more specific information. Bing has Advanced Search as well as keyword options available, and Google has a page set up specifically for advanced search, which lets you fill out your search on the page but also shows how to type the search parameters into the search box.
If you know someone who is really good at digging up links and you wondered how they did it, some of their secrets might be listed above.