I've never properly learned Photoshop. I can resize, convert formats, change the levels and sharpen, but that's about it. I don't know how to dodge and burn or change a palette or all the things that make light look wonderful. So I found this a fascinating hack (someday I may have a newer version of Photoshop that includes it):

Improve your photography with classical art.

When Photoshop entered the CS series it included a new tool called 'Match Color.' This tool was made so that you could match a series of photos to one another.

But there is another thing you can do with 'Match Color' that is much cooler: You can match the colors in your photos to those in famous paintings.

I keep a directory of about 30 of my favorite paintings and anytime I need to do color correction, I just scan through them to find the one that gives the photo I'm working on the best look.

There are lots more examples and a walk-through at that link at Unfocused Brain, via Allsux.