Okay, getting into this really late. Let's see how far I can get in 2-3 days. What I want to do is a character based on Slavic Culture and mythology, a spirit of the lake. Guardian of the local people, shepherd of souls.

So my whole inspiration came from researching lake Baikal in Russia. It is the oldest (or at least one of) lake in the world. There's a lot of awesome things there, a lot history, and a whole lot of ancient life. So I came up with this world where my character exists, where ancient traditions are being forcefully rooted out by new regime who sees it as a threat ( Think of the fall of Kievan Rus)

So my setting is this:
Spirits are a fact, they exist and are known in the world. They are ancient beings their numbers and their origin a mystery. But it is believed that each one has its own “duty”, and is tied to it. This naturally led to formation of small sects dedicated to the spirit they are familiar with. A local religion. In some cases the most devout receive “favours”, granting a more “special” connection to the spirit. Spirits are secretive and rarely seen, unless they want you to, or you are in great need of them. But they are compassionate and welcome those who seek them, provided that the intentions are pure. Spirits can choose a form they appear in, sometimes taking a human form to walk among the villages. However, this world is changing, these small spirit worshiping groups are being hunted. Spirits themselves are being exterminated as they are a source of enormous power, and somebody figured out how to repurpose it.

Navia is one these spirits, and yet she is not as ancient as the others, tho she is old. {Maybe - died tragically in the lake, maybe murdered}. There are a lot of stories about her, and what brought her to the region, none are concrete tho. Records of her appearing in aid of the villagers are only a couple of hundred years old. A very weird case considering that records of other spirits in the world are thousands of years old, if not more. There were no records of spirits switching locations as well, as they seem to be bound to a region. Navia appears in the heavily wooded area, not too far from the village, in or around lake {Baikal-for now} oldest and deepest land body of water that is known of. People see a young woman, in her early 20s, pale, attractive and inviting, her stature proud - almost royal - her clothing un-matching, tattered and old. She guides souls, helps the deceased cross into the afterlife, this is her “duty”, what binds her to this area. She also has a divine connection with water, being able to manipulate it to her will. It is her defence and offence. She does need to be near the water {maybe only the lake water} in order to manipulate it. So in order to defend

After the setting I wrote down some "visual" words, to keep me grounded and help me research the subject better.

Navia - Visual
Based on slavic culture, aesthetic look must match this
Navia - in slavic mythology were water nymphs - character loosely based on this
Appears to be a young woman in early 20s, might the the only spirit unable to change form
Proud, Stern and Welcoming, maybe a bit scared and confused (hint at origin)
Her clothing isn’t aesthetically pleasing, she wears all that she owns maybe clothing is what she gathered randomly from the villagers, also doesn't care much her appearance.
She walks around barefoot,
Hands are not covered
She manipulates water
She’s a spirit in human form, it is a disguise, when she uses her powers this disguise starts to crack (Hands, eyes, legs) reveling her true form, glowing water-like, magnificent, blueish
Her human form is pale, almost too pale
White hair (not too sure on this)
Haunting eyes (strikingly pale, or sharp blue)

This is just a few examples of references that I gathered, I want her outfit/costume to resemble this traditional slavic clothing, but I don't want it to be "study" of this type of clothing. So this would be just reminder, along with some art depicting Slavic deities and references for how her body can change when using her powers.

With all of that, I created some fast sketches, trying to figure out her basic look.

Same situation here 2 days to complete jeje. I like all designs in general are pretty good, i would say that those with long thin fabric and wavy patterns shows the water spirit theme the most.