As has been mentioned, as a new user to PI, real world example uses, and when to use these processes, would be a big boost. I've been imaging for 12 years and can honestly say that I've yet to find any processing package easy to learn. Each has it's own unique way of doing things, which is what separates all the packages. Work flow graphs with additional look up information would also help the beginner. For example, Harry has a great video on processing a galaxy image but I haven't seen anything on processing nebula which is quite different.
Another example is the HDR tool. Lots of options but not sure what they really offer. On one image, the stars got dark in the center, deringing seemed to help this but I can't say why. The only time I ever used deringing was when I did some planet imaging with a webcam and processed it in another software. It had like 6 levels of wavelet processing but other than real time view, I didn't, and still don't, have a clue what I was doing. I guess this is OK but the knowing is a powerful thing.