I am 'The French', I am not a teacher, but if you want to improve your level in English you must work day by day, to learn all the specific rules of this language.
The only way I know is learning the grammar rules, read newspapers or another writting do you like and listen bbc radio or American radios.
It is like a tunnel, step by step you increase your knowledge of English but it's a long way, pratice all the day and one day you will see the light at the end of the tube.
Do not give up and have a nice day.
Student or Learner