Maybe you already know these but there are a couple of really useful ones I've never thought of in Simon Mackie's "10 Simple Google Search Tips." My fave is the first. If you're looking for something that you know is on a particular site:
Use the “site:” operator ... I use this one all the time, and it’s particularly handy because many site’s built-in search tools don’t return the results you’re looking for (and some sites don’t even have a search feature). If I’m looking for WWD posts about GTD, for example, I could try this search: GTD site:webworkerdaily.com.