Writing is an essential part of scientists’ daily life. Writing comprehensible and well-structured papers is a key to publishing; Writing convincing and concise grant proposals is a key to funding. In addition, writing for the public becomes more and more important.
Diction and clarity of the written text is hard work; however, there are great books which could help you to reflect on your mode of expression. One wonderful book is Strunk, W., Jr. & White, E.B. (2000, 1979). The Element of Style (4th ed.). New York: Longman. I not just learned a lot when reading it a couple of years ago, I also enjoyed the reading itself a lot.
I just saw that it is online available here. Moreover, a PDF version is accessible.
As writing a lot makes a successful scientist, but finding time to write and organizing the writing is again hard work, I also found it helpful to reflect my organization of writing. A helpful book for this reflection was Silvia, P. J. (2007). How to Write a Lot: A Practical Guide to Productive Academic Writing, American Psychological Association, Washington DC.
Finally, one recommendation from Christina Schütte’s grant writing workshop last week – of which a preview is accessible on google books – is Silyn-Roberts, H. (2000). Writing for Science and Engineering: Papers, Presentations and Reports. Oxford, England: Butterworth-Heinemann.
Some more general tips on scientific writing are provided by Michael A. Morrison, Professor at the University of Oklahoma.
Please feel free to add further recommendations in the comments’ section!