Since people here are edit specialists (part of the artist clan
)
I'd like to share a few tips of my own. Personally I like to add a little 3d effect on paintings I finish to give it a more polished/retro look.
Here's a tut on it, works with any software.
I managed to achieve something like this on a commission for a friend, only using the original painting I did.
I think it gives a really crisp look. I displaced the blue/red versions by 1-2 pixels only. More than that and it looks bad imo. In this pic I think I used purple/green.
You can also make an artwork look more soft/anime like by duplicating the original artwork layer, putting the top layer in a maybe 8-16 gaussian blur, than reducing the opacity of that layer to between 7-15%. It really gives a pretty and soft look, similar to this: