I have learned more about clipping by sitting on a showbox and watching the good fitters work. Then ask a lot of questions.....Why did you clip heifer A's underline differently than heifer B? Why did you clip one's top one way and the other top a little differently?
The biggest problem I see with some fitters is that they do all cattle generically; they clip everything just alike. You need to figure out what is wrong with your animal and try to fix it with clippers. Not a great top? Go to work with the clippers to make it look better. Not a clean, extended neck? Grab those clippers. Rough shoulders? Use the clippers to make the shoulder look smoother. Remember that clipping is no more than creating an optical illusion. I had a heifer a few years ago that we clipped and clipped and she just didn't look right. We finally took about 1/4 inch off her underline and she looked like a different animal.
Nothing beats experience. Start early so the hair will grow back when you have those 'oops' moments with the clippers.
It will take time and do not get discouraged. You did not learn to walk, write or spell without a lot of time and those 'oops' moments. Clipping is just one more of those things that takes time and determination.
Good luck and hang in there.