A certain aspect: A collector friend some years ago advised us, that a figure's look will always be influenced with the lamp it is lighted during painting and exposition.
Means, if you paint with light from upper left angle (and set lights and shadow accordingly),
you should show your figure under lighting from upper left.
Otherwise you will never achieve the visual appearance, that you had in mind during painting.
You may be sceptical, but I tried it and it is true (not mentioned light bulbs, LED, tubes .... with differing "light temperature").
Just sort it out with two or three photographs of you figures, using different light directions.
So far for basic.
If we come to presentation it becomes a bit tricky:
Having painted all your figures with light from upper left you have to make sure, that your figure in a frame or a diorama gets it's light from upper left and only/focused from upper left.
Otherwise a big part of your painting efforts are in vain, nobody will ever see it.
I confess, by now I never used this knowledge in a diorama, but when photographing my figures I do.
But -of course this all has to be regarded under an different angle when using, say - a lens with round tube or a bat-shaped tube.
Regards
Joerg