My first sprite...

[FillerSprites]

Better! The thing I notice immediately, though, is that the back is too straight. I'd recommend rounding it more right by the neck area. You have a strange mix between sitting and standing, so I'd either pull the front lefts closer in or jut the butt area up a little more to get a pounce-like pose.

I see. The jagged line should be an easy fix. By front lifts, you mean legs? No problems, We all make mistakes.