Well, for starters, animating in 24 fps is fine, but you could do most of that animation in 2s (2 frames for every position, thus making it more like 12 fps). That being said, making movements flow would help. Don't move the arm a cm for one frame, 10 cm the next, and 1 cm for the 3rd frame. That would cause odd, jagged motion which is similar to when the woman is bending over to pick up the object. Also, what might be at play is you moved her slightly backwards for one frame - but I can't really tell. (You don't have to measure every single movement, just make approximations and move as would in real life - starting slow, getting fast, etc.)
Also getting her rigged up so the movements can flow more easily would help, and of course practice.
http://www.youtube.com/watch?v=KB-iPpLf … ideo_title
I made this in 24 fps shot mostly in 2s except when the camera-eye-thing moves really rapidly.

Thanks. I didn't mean exactly 1 cm, but rather to move it at a constant distances depending on the supposed acceleration. I definitely did not move my characters full centimeters at a time, more likely small nudges, shot in 2s.
Look at a motion such as lifting a cup to your mouth - how long does that take? Probably right around a second. Then consider the acceleration at the beginning and deceleration at the end - this might give you an idea for the distance to move each frame.
There's no strict way, it just takes practice to get the feel for how much to move and how many frames to take. If you've seen Coraline, I believe it was filmed in 24 fps mostly shot in 2s.
The movement of the eye-thing was actually edited slightly in post-production to make it faster than when I originally shot it (as smooth as my animation is, my timing is still a bit slow). I sped up its basic movements, shot in 2s, but I didn't speed up its whipping motions, shot in 1s (for which I moved the rig quite a bit each frame). Thanks to our visual processing, it doesn't look jagged but rather smooth - sort of a phi phenomenon).
My main hint for smoother motion is to practice animation and study motion. Try something as simple as moving a coin on a table. Move it different distances to get a feel for the final speed. (This is oft reiterated in stop motion books as a beginning technique for understanding easing effect). Read this if you haven't: http://www.stopmotionanimation.com/handbook/9.htm (as if I haven't already given you enough to read, right? )

It looks like getting the puppet to bend over was difficult, so probably you didn't have as much control over the moves as you would like.
Actually it doesn't bend much,  the whole puppet says fairly rigid and tips over.  I guess that is because it is solid clay and not easy to bend.  (I don't animate with clay so I can't advise on that.)   Either that or she was freezing in the snow!   Shouldn't there be goosebumps?   Not to mention her nipples...   
You need to look at balance - unless she is propping herself up with one hand in front of her, her body weight needs to shift back as she bends so her knees remain under her centre of gravity and able to support her weight.  So the feet and shins would stay on the ground.  The knees would bend and as the thighs go back, she would bend forward at the waist.   Try kneeling on the ground and picking something up, and see what feels natural (and possible without falling over) for you.

Jerkiness is caused by uneven movements, by sometimes not not moving or even moving backwards in the wrong direction, and also when the movement forward is about right, but the puppet also moves to the side for just that frame.  (Of course, if I were nekkid  in the snow I'd be shaking a bit too!)  We can't advance it frame by frame on Youtube, but you could check it in your framegrabber or in QT Player to see what is happening.
Is your software a framegrabber?  With a framegrabber, you should be able to click back and forth between the live view and the last couple of frames shot to see that the movement continues in the same direction.  If you change direction that should also be eased a bit.