When someone has grasped the basic concepts of writing Chinese there comes a point where handwriting starts to look plain or mechanical. From what I have seen the lines look very straight and like someone who has just copied directly from a book.
I know with my own journey I had gradually been given pointers to improve my writing which were simple, but changed my writing significantly to make it look much more elegant.
The two that come to mind immediately were to ensure that radicals were written smaller than the rest of the character and to have horizontal lines slightly angled upward.
What pointers can you give to someone who has a basic grasp of writing so that they can make their writing appear more professional / more beautiful?
This may not be something that everyone does, but could assist someone with developing their own style as not all techniques work for everyone.
NOTE: Please provide concrete, useable answers, not just find some books and copy. I am looking for techniques that are practical and useable.