lerning quickly depends from person, one learn easily , other have more difficult. Don't have "method" to learn quickly. tips to learn - listen in portuguese, listen ,listen!! exerscise your ears, watch movies and vídeos in portuguese with subtitle when beginner after try watch without subtitle, read text , news or something you like in portuguese, write short texts, meet native on internet and try speak portuguese, study grammar and vocabulary (youtube is good ), listen musics and take a letter of music and try sing.
try these way to learn and find the best way to you.