Cats are cute, and cats with ties are even cuter. Is he trying to become a man?
Anyway, as you ask for critique, here is are some tips:
Never choose a darker version of a colour. It looks better if you choose a slightly other colour to shade with (like a dark version of ocean blue for example).
Another tip I can give for pixel art: If you give something another colour without a line between colours (like the orange part on the tail), it's best to draw a few pixels on the edge of that part with a colour which is between those parts. So you can choose orange for example, and then lower the alpha so if you draw on the blue, the colours will mix! I hope you understand this. Good luck!