To learn not only English but any language, four steps are crucial.
1) Reading, 2) Writing, 3) Listening, and 4) Speaking.
Read as much as possible. It will improvise your vocabulary and also will make you understand how to form sentences in various manners.
After reading, writing helps you improvise grammar which is the essence of any language. Writing helps sharpen drafting skills which is essential.
Listening helps you learn new words as well as how to pronounce words. It also helps you direct how to react and respond in various circumstances.
once you complete three steps stated above, final step is speaking.
When your vocabulary is good, you know the formation of sentences, your grammar is sound and you know how to pronounce words, speaking that language will be easier for you after few days of practice.
It is scientific way of learning languages and it my personal experience that this is the manner in which you can learn English.