Can you define fast? I think it is all up to you yourself. Well, pretty much every language is learnt by the same processes which I call them as "The Four Keys Of Language" (or actually communication skills), that is: hearing, speaking, reading and writing. But the most effective way of all is to practice it daily with a native speaker of that particular language, in this case an Arabic speaker. Practice all these as often as you can, and you can master it fast.