CGMythology's Sketchbook

[TrashPanda]

Overall it looks good, I think the main issue is probably the composition itself.
Theres lots of stuff of going on the same time.
I attached you a little very rough layout what I mean.
If you think about a composition like a cocktail glass that has to be filled
with ingredients, you need to be clear what tastenote is your main "star" in the
drink. The mermaid is the clear star and focal point but the other parts like the
rocks, the ship, the treasure etc. dont have a clear visual hirachy.
For example the rock right next to the tresure is bigger than the treasure itself.
The leafs on the right are also bigger than the treasure.
The shipbow is on the same height and size as the rock that is on the same midground plane. 

Sometimes it helps to create these "triangles of importance" its like a moving rubberband
that creates a secondary micro composition within your objects.
The rocks on the front of a coast usually are not so clean, seaweed and moss is often 
seen on the surface. Adding this material would also help to get more contrast tones
into the scene. I hope you dont mind my super rough paintover and nodes.
(Im in the train atm)
Keep up the good work!