What's wrong with my spritesheet?

[Valce]

Hi! I'm a game designer and I decided I want to make the art for my own games.
So, I'm starting to experiment with pixel art.

This is my first pixel art work (my first work for any type of art digital or otherwise, actually); I made it for my upcoming game, City Skate Foranza.

Animations are as follow:
- skate upwards
- skate downwards
- standard skate forwards
- jump
- look back (random idle)



How is it? What should I change? What are the most obvious errors? What kind of tutorials should I look at to correct my mistakes and improve my work?

Thanks for your attention and feedback!

[Ymedron]

The jump is more his feet bending up (making it seem like he is just crouching on higher ground), while a real jump would have the upper body move as well. Im not sure about the game mechanics, but if it reasonably allows for some delay in the jumps, adding an anticipation would help a lot.

When looking back he doesn't look very natural - his head snaps back and forth too quickly. Making it so he turns his head first and upper body slightly lagging behind, and then turning his head forward and then the body to return to the normal pose.
Humans prefer turning their head to their body and will avoid it until a little bit after their shoulder, and then they turn their body to give additional turning.

Hope that makes sense.