How can I improve my editing process?

I have recently transitioned to Gimp, and looking for ways to improve/optimize my process of these repetitive edits. I often do 150-200 so even the slightest optimization can save me hours!

I know how I could have done these much faster on Photoshop, with batch actions, and even would have gotten a better result, but I am fairly satisfied with the result for this first attempt.

Already noticed errors, are the feather edge of the select tool. I should have increased the feather to avoid the visible edges when adjusting levels of the face area.

Also, I should have taken better pictures to start with!

That said, resizing each picture separately, seems like a waste of time. On Photoshop, I could set the crop tool to crop resize the cropped image to a set dimension and resolution, even if i scaled it. I could also freely rotate it. So just the crop tool, saved me 3 steps per picture!