Simply by watching movies and get the subtitles from the audio. The speech never match the subtitles but you can get a native speaker to help you to write 10 minutes at the time. Get the translation and type it on word. With google translate get the approximate phonetics at the bottom of translation. Then use an iPad or Adobe reader to speak word by word. Practice and do your best. Then get a native to correct your mistakes. When you speak use the same emotions and intonation like any good actor. The Use of emotions is very important.

Try watching English movies without reading the subtitles and read more English articles and books and.also u can listen to English songs and news.that helps alot