Hi stargazerkira! Welcome to the forums 
As for your piece, it has a lot of good things going on so my main suggestions will be more about the lighting and textures.
So first of all you have three light sources. One from above, the two shiny plants and the sort of lava stream at the bottom. The plants may affect the surrounding area and character a little, but the lava's effect would probably stay at ground level.
As you already did on your picture, the main one will be the one coming from above, but I think you could push the effect even further by making the shadows area darker and more defined.
As you may have also noticed I did a few other things. First there's the textures on the rock. I may have overdid it, but right now yours look too smooth. Just adding some cracks and wear could help making them feel more rock like. Then also I increased the size of your character's left hand because if you compare it to his right it's way smaller. Finally I also painted over the bubbles a little bit with their surrounding background color just to have them blend a bit better with the rest. That may not be necessary though
And one last suggestion that I have would be adding some foreground elements to add even more depth to the scene and make it feel more real I guess. I did it really roughly just to show you an example. I tried it using the type of algaes you already did and keept them blurred and undefined to still keep the focus on the character. It's really rough, but hopefully it make sense.
I hope this was helpful and I'm looking forward to see where you take this piece. It's pretty nice!
