I'd like to learn

[Vipershark]

image posted for reference since it's a new page

Okay, first things first, please don't ONLY post the big version of your sprites.
You should always post them at their original 1px scale (as well as the bigger versions for detail if you choose to do so) so that the sprite can be seen how it's meant to look.

Anyway, now that you've gotten rid of most of the jaggies, you're left with lines that are cleaner yet are still sort of all over the place. Notice how the top of the hat looks bumpy instead of being a smooth curve and Mario's nose looks sort of octagonal rather than round, for example. Your next step is to go in and clean up your curves and and lines to get your lineart looking good.

I'd post an edit along with this but I'm on my way to work.
I'll probably do one later tonight.

edit- Make sure you look at a good reference when cleaning your lines.

[FinalSmash]

I would post both, but Paint won't let me duplicate the image.

And I was actually going off of this because I couldn't find that picture.

[Vipershark]

You can duplicate in Paint. I showed how in the video I did a couple pages ago.
Copy, paste, and then scale the pasted image without deselecting.

Anyway I'm still at work so I'll post more when I get home later.

[FinalSmash]

But that's the problem; it won't let me copy anything.

[Vipershark]

What do you mean it won't let you copy?
Are you using the selection tool beforehand?


Okay, I went through and cleaned up a few things, particularly the top of the hat, the nose, and a little on the ear. (Mine is on the right)
It's not perfect, but this is the type of thing you want to do. Look at your reference and try to follow the curves and proportions.
I removed the shading for now since there's not much use in shading if your lineart isn't ready but that will go back in next.

So from here, go through your sprite and do your best to clean up the lineart and make it accurate to the reference I posted above. There are several areas that you want to look at in particular, such as the shoes, the gloves, the buttons on the suspenders, and the mustache.
Also, if you compare the sprite to the ref, Mario's head is too far down and to the left and is sort of resting on his shoulder rather than in the middle where it should be.