Use the CRAAP Test to judge whether you should cite a given source:
Tips and tricks for Google searches
Use quotation marks for exact words or phrases.
Use OR to search for one word or the other. Google will find pages that match either of the two words.
Use site: to search within a site or domain (no space after colon).
Use a minus sign (a hyphen) to exclude a word or phrase from a search.
Use allintitle: to show results with word(s) in the title (no space after colon).
Use related: to search for sites similar to ones you know (no space after colon).
Use link: to find sites linked to a particular web page (no space after colon).
Use filetype: to restrict results to certain file type (no space after colon).
Use two periods without spaces to search for a number range, such as dates, prices, and measurements.
You can also use a Google Advanced Search to construct your search.