The best way to improve your English in a very short time is to sign up to an immersion English course. This is a course where you spend a week (or longer) in the company of native English speakers and other learners at which every single word spoken must be in English. It's a trial by fire but in my experience, very successful for most learners.
However, I don't know if such courses are available to you.
Are you taking English classes somewhere? Do you read English books, newspapers and magazines? Do you listen only to English-speaking radio and watch all TV and films in English without subtitles? Do you practise your English with any native speakers on a regular basis?
Student or Learner