I recently sat in on a Web presentation from the fine folks at Capture One software. Whilst the video was based around improving your landscape images, I found that a lot of the advice and overview were useful for many different types of images.
In particular, the difference between changing brightness and exposure was very helpful, along with curves and levels. I use all these settings but now have a better understanding of how they interact with each other and which areas each change affects the most.
I am including the YouTube recording below and recommend watching if you want to understand fine tuning your adjustments.