Advanced Google searching can improve your results dramatically. Here are some of the most useful commands:
site: searches one website or domain. Useful when a website's own search engine is less than helpful, or when wanting to search only a certain country's sites or type of sites.
- (minus sign) excludes a word from your search results. Can be used in conjunction with site: to filter out results from a particular website.
intitle: searches for your keywords in the title of the website - often increases the relevance of your results.
The Search Tools button at the top of your Google results gives you a variety of other options - you can limit your results by date, use verbatim to search for your exact keywords, and more.
For more tips, see the links below: