Learning to use the English language can be challenging. There are quite a lot of people who speak in English but they use it wrongly making grammatical errors all the time. The best way to learn English is to put yourself in an environment that is full of English speaking people surround yourself with the language.
learn English in the UK in order to be amongst people who use the language everyday. The native of the UK have used English from the moment they could say "mama". Get friendly with the people of the UK and spend lots of time with them. They will understand that you do not speak English well and correct you when necessary.
English language courses are available that will help you increase your vocabulary. In order to speak English well you must learn as many words as possible. A limited vocabulary will only make the task of learning to use the language more difficult. Learn how to use slang but do not concentrate too much on this.
You should also try to think in English. This can be quite difficult if you have grown up thinking in your native dialect. Thinking in English helps you to get a firm grip on the meaning of the language. It also means that you will stop doing mental gymnastics by thinking in your native language and then trying to translate it into English.
Learn the meaning of the words and the context that they are placed. The word knock can mean plenty of different things. "There is a knock on the door" means something different from "Yesterdays drinking spree really knocked me out". The first one means that someone is at the door knocking it. This is a verb and means the actual physical knocking of the door. The second one means that the drink had an adverse effect on you. It doesn't mean that the drink literally knocked you off your feet.
English Summer schools are a good place where you can surround yourself with enthusiastic students who will be willing to help you with the practice of the English language.