Hmm...well, the test is a bit stiff at times. You really should just animate at the frame rate you're comfortable and good with. Also, if you do want to do 24 fps, as other people have said, if it looks too fast, put a frame in between the keyframes.
But to take it a step further and make it better, mak your core frames, as in, the most important parts of the animation, and then fill in the frames in between them with keyframes so they are alot smoother.
In other words, instead of adding a frame between the keyframes, add keyframes between the keyframes so it is alot smoother.