Here is my compilation of all the Google search tips everyone should know about.
Search within a range : You can search in Google within a desired range. You need to type in the range as separated by .. but make sure you specify the unit as well.
For example: LCD 21..32 inches
Synonym Search with "~"(Tildy) sign : If in case you want to search for the term as well as its synonym, then just add the ~ sign in front of your search term, you will see the links for the same terms synonym.
For example: ~fun~image would return fun image as well as joke image, humor image, joke pic, etc.
Omit certain word with "-"(minus) sign : If you want to omit certain word, you can add the "-" sign in front of your search term.
For example: if you search bill microsoft, you'll get all the results relating to Bill Gates and Microsoft, but if you search bill -gate microsoft, you'll get the real bill about microsoft.
Definition search : You can use "define:" to search definition of a word.
For example: if you search define:lcd, you will get definition of lcd all over the net, it's more complete than Answers or Wiki.
Use of "?"(question mark) sign : If you are uncertain about the spelling of the word or you want all possible words, you can use the "?" sign.
For example: if you search sun?day, you can get results such as sun earth day, or the word sun-day.
Use of "*"(asterik) sign : Not sure about how it's different with "?" sign. But you can try the example and you'll understand.
For example: if you search friend*, you will get words like friends, friend to friend, friend society. Compare the result with ordinary friend search, you'll know how to use "*"
Search for exact phrase with quotation mark "": If you want Google to search all the words you type, use quotation marks. This feature is available in Advance search feature too.
For example: if you search "just like that" with quotation, you will get results containing exact phrase "just like that"
These tips are worth knowing and you should try all of them, they'll be useful for you one way or another. As Google is always tweaking their search engine and algorithm, I'm sure there'll be more interesting tips always.