Practice and practice..this helps in learning. if it is necessary to learn it very fast then listen carefully when others talk in that language and try to understand. you can take the help of tutors or online courses or book courses. if you know to talk but not to read and write, you have to take the help of your friends or teachers. if you have a problem in writing and reading, try to read books in that language. read them slow but please read them. and another point..any language cannot be learnt in haste because haste is waste. try to learn it slow pace then it helps in picking up the language faster. i have experienced this. so if you follow this method it can help you at-least a little for sure.