Pixel art isn't a style, it is a medium, and there are many, many styles of pixel art!
Your lines look blocky. It's hard to explain in text, but check out the first example in this tutorial. Your lines are resemble the "no" example, and as a result look uneven. It's a good tutorial overall, I recommend giving it a read!
You're using a lot of low-contrast colours that don't stand out from each other. That's generally just a waste of your time - why spend time drawing details and picking colours people aren't going to see unless they're zooming in a lot?
For example, there's a lot of form definition on the character's face. Their cheeks puff out as they smile, there's some indication of their nose. Is any of this visible? I'm zoomed in 20x and still have a hard time making it out. If it's important, it's wroth using high contrast colours to show. If it's not important, it's probably not worth drawing at all. With small art especially, you have to be very selective with the details you choose to include. Choose poorly, and you'll end up wasting your time in the best case, creating what reads like noise and hurts the overall readability of the sprite in the worst case.
Thanks for the advice :)