Whole books are written about this, and there are now many good tutorials available on You Tube. All I can do is express my personal choices. The most important thing is to use the photo processor with which you feel comfortable, and which delivers what you need.
I have found the tutorials published on You Tube by Peter Morganti particularly helpful, and links to some useful procedures are shown on the right. Not all his tutorials are included. Check his You Tube page for more (incl Lightroom and Photoshop)
For many years I have relied on Serif PhotoPlus for image processing. It almost matches Photoshop (which is the industry standard), but at a much lower price.
In recent times, Serif and Adobe have tried to develop cataloguing systems for digital images. Here, I am afraid, Serif has not done quite so well. Moreover, I sought expert advice about the products, and was told that Serif PhotoPlus works well, until you start shooting pictures in Raw. He recommended the use of Photoshop Elements. I switched to this a couple of years ago, and I can confirm that the Elements Organiser works better than the PhotoPlus organiser.
However, I find that for processing screen grabs, building composite images and some other functions only otherwise available in the fully featured Photoshop, Serif PhotoPlus has a useful role, so I run both.
That said, most of the processing of my own photographs is now handled in Photoshop Elements, including
- general retouching, straightening and cropping
- generating cutouts,(the Elements functions are so good that I rarely use my Fluid Mask software)
- creating panoramics by stitching photos together
- increasing image resolution (using a Photozoom plugin)