In school, as children, we learn new words via spelling tests we are assigned by teachers. They give us a list of about 10 words at a time; we learn their meanings and use them in sentences so that we understand how they are used. We also learn roots in school. I tell my students to learn roots because it will enable them to decipher many English words. The problem is that the Latin roots won't help with the words rooted in German. English is a Germanic language which has words rooted in and drawn from other languages-- and it's ever changing (this is why it can be sooooo hard to learn). The best way to remember vocabulary is to read books/articles/etc. and look up words as you're going along. It's tedious, but effective.