Improving English is difficult but not impossible. With efforts you can very well improve your communication. Take the case of our Prime Minister Mr Narendra Modi. If you watch his speeches of 2013 or 2014 and 2015, there is a big difference. Now he speaks English well. It appears that he has mastered English after becoming PM.
Note the following points:
a) Concentrate on communication as a whole, knowledge of language is secondary
b) Give emphasis on the sequence of the communication in whatever language you speak or write
c) Certain words have to be used at certain places. Usage of those words bring punch in what you speak or write, therefore, improve your word power.
I have given my comments on how to improve one's spoken English. Click the following link to refer it:
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More than seven years ago, I have given reply to the similar query. Click the following link to refer it:
All the best!
Please click on the following link to get various suggestions made by members on tackling the problem of improving your communication skills in English.
Speaking, reading and writing, in that order, holds the key to coping with the problem you have indicated.