Vocabulary building is simply a matter of reviewing the words regularly until you fix them in your memory. This is best done by setting aside a specific amount of time each day for vocabulary study. During that time you can look up new words you have noted during the day and review old words you are in the process of learning. Set a goal for the number of words you would like to learn and by what date, and arrange your schedule accordingly. Fifteen minutes a day will bring better results than half an hour once a week or so. However, if half an hour a week is all the time you have to spare, start with that. You may find more time later on, and you will be moving in the right direction.