Immersion is the key. Try to do as much listening as you can in English during your day: Radio, TV, Podcasts etc.. Your brain will pick it up and you will tend to learn quicker when you combine this with your usual learning.

Even better than flash cards, Try www.Memrise.com. I use it for learning Chinese, and it reminds you at proper times to ensure maximum retention. I love it, and you should be my friend on there if you decide to try it out :) I'm pretty sure they have high level English vocabulary, and you might like the SAT vocabulary lists. (Most English speakers do not know all of these words, but those with a higher education usually know most of them) The SAT is basically a test that Americans take to get into college. If not, you can always make your own flashcard sets on this website, too! They have a huge database of words, and interesting ways to remember those words. :)

Make a set of "flash cards".You can buy some index cards. Then write on one side the new English word and on the other side the word in your own language. start with 5 to 10 words a day. First look at the English word and say it in your own language. Then turn the card over and check if you were right. If you were right then put the card on the table by your right side if wrong then put it on your left. After you have finished take the cards on the left and practice with them until you know them. Next step is to reverse the process. Look at the word in your native language and say it in English Repeat the process as before.