I have 'some' experience in animation itself, in 3D, that you might be able to use. Always use references to get the general movement and pose of how characters should be. Keyframe the most important points in the animation before you start doing the in between. -Dont try to get the animation right the first time or even attempt doing it frame by frame.
*Ignore the dress...
Hmm what else...Depending on the animation, it should have end recoil. I think what kinda "breaks" an animation is the flow. You have to keep everything smooth(most of the time), and avoid making it stiff. The hardest part i found when animating in 3d ,at first, is making different parts move individually, while still having it look like one unified fluid motion. From what i remember back then, i believe i broke the stiffness after creating the main keyframes. By removing or adding them to bones individually instead of to the whole. Take a look at this animation i made a while back :
Despite the animation being mine, i think that animation looks pretty smooth. Theres no big recoil for something that is supposedly strong, due to the character being very stable in that pose. Also notice the "snaps" in the animation that create the attack itself. Anyways, with this animation, the biggest thing i wanted to point out was the non-unified way of the body parts to break the stiffness. The most dramatic is the front leg turning, while the rest of the body turns in the opposite direction to build up power.
In the end though, nothing beats hardwork and many small edits and tweaks to improve it.
*animations made in brawlbox
*gifs made with screenshots, which explains some of its jumpiness, atleast for the last animation. I improved the "screenshots" by making a small program to take snapshots of a given viewport, which explains why the first animation isnt as jumpy.
*i havent used BB in over a year,nor have i animated in 3d since then. These animations were made over a year ago.