I'm not a big fan of Adobe products and Affinity is a very nice alternative providing all that you need for cleaning you scans. With that said, many of the terminology and tools used in this guide can also be transposed for usage with other image editing software like Photoshop, albeit with a slightly different GUI. As of this writing, the price for Affinity is lower than Photoshop (in case you want to buy a software). After 150 scans, my work flow got stable (I dare say, optimized even) and so I decided to make a small write up of how I do things.
Affinity's default setting do not require much tweaking. But I highly suggest changing the zoom behavior.
Edit -> Preferences or CTRL + , and uncheck Use mouse wheel to zoom.
You can still use a wheel with CTRL to zoom in and out.
In general, get used to switching between different zoom levels. I use these 5 hotkeys:
CTRL + 1 100%
CTRL + 2 200%
CTRL + - Zoom out
CTRL + + Zoom in
CTRL + 0 Zoom to fit
Z + draw an area with mouse Custom zoom
First of all, you should make sure that the scanned image is properly aligned. If not, you need to straighten up the scan. Press C (Crop), you should see control nodes in all four conterns. If not just click Reset button.
Now click the Straighten:
I usually choose the steam as my control line. So you basically draw a real line in the image and it is going to be rotated by the delta.
Now let's do some cropping. I always start with it using the custom zoom in the top left corner.
Press C (Cropping tool) and you should see something like that:
Move the node point to the right spot and press ENTER. The image will be cropped. Now I zoom in again and go along the picture checking if everything was cropped alright. And then modify the top right node point. Pretty straightforward.