Lightroom tips are a lot like puppies: you can never have too many of them. And while I can't offer you a puppy (likely because I'm keeping them for myself), I can offer you this great video that will give you 25 helpful Lightroom tips in just 2 minutes.
Coming to you from Christopher Burress, this excellent video will give you a quick overview of a bunch of useful tricks and shortcuts for working in Lightroom. They might seem minor, but if you spend as much time as I do in the program, they'll add up to substantial time savings and make your overall experience more enjoyable. What I particularly appreciated was the focus on shortcuts that minimized the amount of mouse movement, which is particularly helpful when you're using something like a brush and don't want to mouse back and forth across the screen to adjust its sliders. A natural way to edit in Lightroom is with one hand on the mouse and one on the keyboard, so the more keyboard shortcuts you know, the more you can minimize such movements, which of course adds up to better efficiency in the long run. There are a few other tips not related to mousing you'll likely find useful as well.