make word-lists and memorize them

Reading about something you are interested in. It will be easier to remember new words. Writing or talking to someone about it to remember words (and to learn others).

By reading... Here for you: http://www.italki.com/article/36/learn-english-twice-as-fast-by-reading-the-sunday-paper#.U0z3Wlf4KU4

Is to study more of its, because the more you study, the more it will become natural to you. Its just like a habit, the more you do a particular thing again and again; the more its become your habit. So you will improve your vocabulary by studing..