I checked your portfolio. My general impression and suggestions:
- I would break it into two seperate portfolios. One with fantasy/sci-fi and other with cartoony.
- This is something I noticed in my own art too. I'm still struggling with it and it is easier said than done so take this suggestion with grain of salt. I got the impression is you seem to put more emotion into cartoony art and you enjoy it more. Maybe beacause simplified design allows you to communicate expression of characters easier. If you focused more on expression when painting realistic characters (instead of just anatomy and costume design), you could give your artwork same dose of energy and it would resonate more with the viewer.
- In the swordgirl artwork I'm not entirely sure if it's character design or illustration. You give large amount of space dedicated to background but it doesn't really add much to the whole image. If you do illustration then the character and the background work together as a whole composition and character relates to the background. In that image she is standing in the shadow of the column and catching highlights on her arm and legs at the same time which kills the illusion of being there. I tried to crop the image so that in the new composition you get more focus on what is she doing and there isn't so much unused space. I think it works a little bit better.
On the other hand if it was the typical character design then the neutral pose with no background would work better.
- If you want to do robots and mechanical stuff profesionally then I would practice that more. There are some good ideas in the mule robot but the forms look very crude like it was constructed out of carboard boxes. The hinges in it's feet doesn't make much sense.
- In the creepy creature with blades instead of arms and legs you highlihted silhouette on which there isn't much going on. On the other hand most interesting parts like face and blades are hidden in the shadow. I think it would have more impact if you revealed a little bit of more these things. Of course not in the most direct frontal way beacause that would kill the mystery and horror you were probably going for. Also bringing more color variation would make the image more alive.
- The character with obelisk on his back is very dark and has no focal point. You could try to give him spotlight with strong falloff effect. I mean by that the cone of light where it's core has much stronger intensity than the edges. Someting like this.
Also I'm not sure if the symbols are shiny or painted on top of the armour. If they are shining then going for very strong white wouldn't harm the character much.
- In general use more cast shadows. By using them you hit two birds with one stone. More realism and by casting them on some interesting surface you can show it's shape and texture at the edge of the shadow and light.