My photoshop skills consists of a few tricks and tips I learned by sitting next to pros or asking them. Like using the curves (under Image >adjustments>curves) or the very handy resizing of images within an image (Edit>transform>scale). But for a while now I’m using Totally Rad after reading about it on the blog a Beautiful mess.
It works like a set of photoshop actions. You buy and install them on your computer and then under the filters you find rad lab. It’s a bit like the filters that you use on Instagram but with a lot of more options. Within each filter it’s possible to adjust the different layers. This is a very good tool!