So don't put a lot of effort into proofreading until you are sure that what you want to say is the best you can come up with, then you can spend more time on fixing up the writing so that the punctuation, spelling, etc. is correct. More experienced writers rewrite more times and more substantially than less experienced writers. Good writing takes time for everyone. So give yourself time to rewrite so that your readers see the best of your thoughts and writing, not the best you could come up with at the last moment. Ask friends, ask professors, ask your writing advisor in languages.
Good writing takes practice.
The only person who can make you a better writer is you. So work at it, show your work to other people, and rewrite, rewrite, rewrite. There are plenty of writing handbooks and guides available. Of course, the way you write depends very much on what suits you, and what suits the particular piece of writing you are working on.