DearAmit,
The moment you think, you are not good, you become that. Always think good, you will become good. There thousands of people not your standard in writing, when I see your communication. for learning swimming, you should jump in to water, like that to improve your English,:
1. start conversing in English to every body. Let you make erros, never bother; go on talking.
2. Read a lot. Read Editorials of any leading English newspaper (The Hindu, Times of India) loudly
3. Write more English
4. Listen to other convering in English ( listen to BBC News, CNN,NDTV etc)
5. Go & attend all the English debates, discussion, meetings happenings in your town
I am pretty sure that you will become good in less than 6 months
Regards
shyam Kumar