I referenced some stock, Princess pack by =lockstock on deviantart for the girl (Changed her up a bit of course) as well as some medieval artwork. Specifically "Unicorn at the fountain" and others in that series for the foliage and to get that medieval look.
I didnt do the massive bushery like those old paintings, I just referenced the types and styles of grasses and stuff.
As you can see I used almost all warm colours except the area where the unicorns horn touches the water.
Also I used a cool grey on the dress, just to make it stand out a bit and to make a bit of a link between the purified water and the pure medieval maiden.
Watercolours on Watercolour paper, with some Acrylic