I agree w/ the "relative scaling" concept. Not in the sense of PNU vs. inches or centimeters or whatever, but visual comparison of elements of yr scene.

I highly doubt anyone is gonna take a ruler to yr pic & say "Oooohhh.....that chick is only 5' 2". She's tiny". However, it is a lot more resonable to infer that someone will notice Figure A only coming up to Figure B's shoulder & making the same observation.

A 'nother "scaling tool" worth mentioning is common real-world objects. Yr average household doorway is approximately 80" tall....so by placing the same 2 figures near a door, if the doorknob only reaches Figure B's sternum, one could reasonably assume that "Holy Holiness...Figure A is a freakin' MIDGET!!!".

Obviously this method won't always work (not many doors to be found in forest scenes, fer example), but w/ a lil' lookin' 'round the room yr sittin' in ya can prob'ly find/ tink of a common real-world element  ya can toss in yr scene to give a sense of proportion.

...or sumpin'

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