To perform any photo restoration basic techniques are essential. Understanding how to make something look un-restored is what photo restoration is all about.
Edges / selection.
When anything is moved or copied over you should match the edges. When you are selecting something new to insert into an image you should match the edges. Matching edge definition is my number one tip. Edge selection video.
If you are inserting anything into an image especially skies, match both the edge definition and the grain. Old images have natural random grain that doesn’t mix that well with flat computer generated tones. Skies will look fake and nasty. If inserted with bad selection they will look even more amateurish. Matching grain video
Don’t take short cuts
Taking short cuts with photo restoration is very tempting. Do it quick and make a fast buck! Do this this and it will come back to bite you! Initially you may benefit by making fast money but as soon as your techniques are exposed by some simple image brightening your reputation will plummet through the floor and you will soon be out of pocket. Don’t take shortcuts with photo restoration
Make it real – do not make it up!
Inventing detail or making up obviously fake bits of the image doesn’t make a “restoration”. What makes the restoration is genuinely thinking about the restore and what should be filling those missing pieces. We don’t want smooth edges when they should be sharp, or smooth textures when they should be grainy or nasty cloning. We need to see nothing, no obvious signs of restoration anywhere. Carefully matched grain, no “invented” details and artistic interpretations of what should be there. Restoring a photo with a natural eye.