Characters and writing them.

Some of you have more experience, some less. I just wonder. I am not too bad at characters, I remember them, read them and write them. When it comes to writing I have a problem, no matter what my characters don't look nice. the radicals are too spaced apart, or the ideal square shape becomes rectangular. I tried learning to write better by using the tracing copybooks (one page has characters printed, then there is the transparent paper on which you write by tracing) and also I am trying to use the grid paper as much as possible. Still, not much improvement. I write with a fountain pen (my writing in other languages is legible and pretty neat). Any tips? Maybe some better exercises?

Thanks in advance.