Copying and pasting text is something everyone does. In OS X you have two choices by default -- copy and paste, which retains formatting; or paste and match style, which strips out the source formatting.
If you're like me, you almost never want the source formatting. Cmd+V is the shortcut for regular pasting and Cmd+Shift+V is usually for paste and match style. However, depending on the program, the latter's shortcut is sometimes Cmd+Shift+Opt+V, which is a bit of a stretch for my poor fingers.
You can streamline this process using FormatMatch to paste plain text at all times. When enabled, the menu bar utility makes pasting plain text the primary function for Cmd+V. A keyboard shortcut will disable FormatMatch when you want to retain styling. While it solves one of my pet hates, I wish you could disable the menu bar icon.
If you're like me and almost never want the formatting to come with the text and can't remember the right shortcut key combo for paste and match style depending on the program, then check out the free FormatMatch from the Mac App Store.
Alternatively, if you don't like the switchable app approach, you can swap the shortcuts for paste and paste and match style as this tip suggests.