For castanic, just touch your face to get a feel about the proportions, then adjust the sliders accordingly and fine tune to your liking. For elins the main focal points are to make the jaw not look like a duke nukem one, to keep the eye distance reasonable and to not overkill it with the cheek size.
By the way your elin model's mouth is only good for screenshots (except for ninjas. It's fine for that). If you make the mouth like that, it'll gape open on idle loop.
It would be best to take a little time running around Highwatch, taking close-up screenshots of characters you like. Then take your time with the char creation tool.
Here's a few Elin random screenies:
Here are some presets I made for myself to use: http://imgur.com/a/pvlOd
That face preset has weird pointy nose
Sharp pointy nose good, extra damage to enemy when you facetank hits from it :c.
