AoA,
Make your habit of reading DAWN on daily basis. Read editorial page completely and take bird's eye view of important national and international news. Highlight those words which you don't know and get their meanings checked through dictionary. Once you make your habit, it would be quite easier for you to learn. Plus, you should also download GRE vocab as it's very useful and important as well. The meanings are explained for every word.
Set your goal to memorize 'ten' words per day with proper understanding of their meanings. You can get proficiency over 3650 words (10*365 )in a year if you memorize just ten words per day.
Here is the link to download GRE vocab:
http://www.majortests.com/gre/wordlist.php
Best of luck.
Stay blessed.