If you are not a primary English writer means your primary language is not English and you face difficulties in English writing don't worry I will tell you the best method.
Go to grammarly.com in Google and download the app and then sign in with your Google or FB account now select it as your keyboard when you are writing English.It will automatically correct your Grammar, spelling mistakes and also punctuation marks will also be sort out.
So what are you waiting for go and use this if you want to learn English quickly and want to improve your English.
Thanks for the info I'll be sure to visit that to improve much more my grammar skill:)