David Pogue has a good bunch of basic tips and tricks. Hardly anybody at all know them all.
This one for instance will help me daily:
In Microsoft Word, when you paste in text from another document—say, a Web site — you may not want all the boldface, colors, fonts and other formatting from the original source. Instead of using the regular Paste command, in that case, open the Edit menu and click Paste Special. Click Unformatted Text. You’ll get just the text, without the fanciness.
This also works works when I paste text from a web site into a blog post. I select Edit/Paste and match style. Previously I had to change back and forth between "compose" mode and HTML mode in the blog posts. Otherwise I'd get a big mess of formatting in the middle of the post. (Not sure why that is default.)