- Tips
Read more material
Practice writing
When you want to write your ideas in the manuscript first explain your idea to someone, if they cannot understand you then they will probably not understand your writing either.
Plan the way you write your manuscript (Plan/write/review)
Don't make your reader bored (ask your self would you like to read what you just wrote?)
Force yourself to write - don't write only when you feel like it.
Revision (don't be rushed after someone checks the manuscript for you).
Don't be scared to reduce the word count of your manuscript.
Ask someone to edit your paper (a friend or college)
Read the style guide of the journal! (Very important)
Finally, just understand that everyone thinks that scientific writing is not easy.