i like the angle you drew diana in, looks pretty solid.
although the water ripples look well placed, the brush strokes could use some variety, because they just look like scribbles and it's kind of repetitive.
also there's quite a bit of empty space in the top right area. to avoid things like that, you could have diana's shadow cast farther behind her. you could also add a concrete texture or add tiles to the floor so that it wont look like one flat color.
just some tips to keep in mind for next time