Use the book English for Hindi Speakers by Dr. Paul Pimsleur or a similar book that specializes in English for Hindi speakers. The Pimsleur method has been celebrated world wide for its ability to help non-native speakers learn English rapidly. This book is tailor-made for people whose first language is Hindi. It comes with a compact disc (CD) for pronunciation. Do all of its suggested tasks to maximize your absorption of English. Set a schedule if you have trouble keeping up with the exercises. If you carve out time each day or every few days, you'll be much more likely to complete the exercises.
Learn the English alphabet and the pronunciation of the letters. This is of utmost importance and can be done via the Internet; a website is linked below in References. The English alphabet differs extremely from the Hindi alphabet and is the foundation for forming words and sounds.
Quiz yourself on the English alphabet. Make flash cards or do online quizzes to make sure you're able to pronounce the letters correctly.
Obtain a Hindi-English dictionary. A version for download is linked below in References. A hard copy is handy because you can carry it with you at all times.
Take an English class in your area. To find a class, check with your local university or high school. Ask about English classes that fit your schedule. Take your class seriously and do your homework to maximize your learning.
Join a local English club or American or British expatriate group to meet for conversations. Check with a university or newspapers to find such organizations.
Go to your local American Corner (see References for a list in India) and participate in activities such as language clubs and movie nights. Check out magazines, books and CDs in English as often as possible to get your mind thinking in English. Listen to songs by English, Australian and American bands. Look up the English lyrics to your favorite songs online and print them. Listen to your favorite English songs while reading the lyrics.
Be patient with yourself. Learning English is not easy, especially when the learner's native language has such a different alphabet, such as Hindi does. It can take years to master a language fully. Stick to it, and don't be too hard on yourself. If you begin to lack motivation, think about the rewards learning English will bring.