Hi Maheshwari,
It's not as difficult as it seems. Daily, read the newspaper. Make sure you read it loudly and at least 12 to 15 articles from the newspaper. Watch English serials and news channels. Use the English language as much as you can with your friends. Be confident even if you are not fluent in using the English language. If you are worried about an interview, then practice basic interview questions like "Tell me about yourself" and hobbies before attending. Search the web for materials and presentations on English. English is not our first language, so it's very normal to be unfamiliar with it, but it is always good to learn by practicing daily. All the best.