Here are a number of excellent online resources to help improve your writing skills:
icipe Scientific Paper Writing Workshop 2016
icipe Scientific Paper Writing Workshop 2016
AuthorAID
This is a global network that provides support, mentoring, resources and training for researchers in developing countries. AuthorAID helps researchers in developing countries to publish and otherwise communicate their work. It also serves as a wider global forum to discuss and disseminate research. Includes lots of training materials. Registering is free.
Elsevier Publishing Campus
Elsevier’s new online training center includes instruction on writing for books and journals, peer reviewing, grant writing, ethics - and how to get your research noticed.
http://www.publishingcampus.elsevier.com/
Research4Life Training Portal
A platform with free downloadable resources for researchers. The Authorship Skills section contains 10 modules, including how to read and write scientific papers, intellectual property and web bibliography along with hands-on activity workbooks.
http://www.research4life.org/training/
Career Advice portal of Elsevier Connect
http://www.elsevier.com/connect/story/career-development/career-tips-and-advice
Stories include tips for publishing in an international journal and “Eight reasons I rejected your article”.
COURSERA
Online course on How to Write and Publish a Scientific Paper
Writing for Journals: Online courses
Tips to Writing better papers
https://www.elsevier.com/connect/infographic-tips-to-writing-better-science-papers
How to publish in scholarly journals
https://www.elsevier.com/__data/assets/pdf_file/0003/91173/Brochure_UPP_April2015.pdf
Research and publishing ethics: Authorship, plagiarism and responsibilities
Elsevier Publishing Campus: Quick Guides, Brochures and Papers (RECOMMENDED!)
Getting published: What distinguishes a good manuscript from a bad one?
https://www.elsevier.com/connect/get-published-what-distinguishes-a-good-manuscript-from-a-bad-one
Writing in the Sciences (Coursera online course)
https://www.coursera.org/course/sciwrite?action=watchlist
Publishing and Research Ethics
https://www.publishingcampus.elsevier.com/pages/63//ethics/Publishing-ethics.html
Write that Journal Article in seven days
Shut up and Write!
http://thesiswhisperer.com/shut-up-and-write/
How to Read a Scientific Paper
http://www.research4life.org/how-to-read-a-scientific-paper/
Written Communication
http://www.northwestern.edu/climb/resources/written-communication/index.html
The Structure, Format, Content, and Style of a Journal-Style Scientific Paper
http://abacus.bates.edu/~ganderso/biology/resources/writing/HTWsections.html
Becoming a "Jedi Writer"