Besides using the golden ratio that has already been said, proportion in terms of realism and non-realism depends on your preference.
If you look in art books, comic books, and so on, proportion depends on the type of charcter being pictured.
Superman who has to look impressive will have non-realisitic proportions, same as Wonder Woman.
Personally I like to be more-than-real, so my legs are a bit longer than normal and I tend to wear more skirts and dresses to accentuate my longer legs. Visually, you cannot tell, but by using the Golden Ratio, I am off-standard.
Best things to look is to either use the Golden Ratio or to use art/drawing books for proportion standards.