One of the best ways to improve your vocabulary is to read. Choose things to read that you can understand but which have a few words on a page that you aren't sure what the meaning is. Mark the words you arent sure about. You might even want to write them down in a list. Looking at the sentences around that word, try to figure out what it means and write down what you think. Then look the word up and write down the "dictionary definition." Look back at the sentence and your own definition and see how close you were to understanding the word. When you have spent that much time on a word you will probably remember it, but you can also review the words and definitions once or twice a week to help you remember. Last, try to use your new words in writing or conversation!