Following vocabulary books, for example Barron's 1100 Words you need to know, is a great way to gain a lot of vocabulary, but if you do not use them, you will forget them. However, there is another approach which I keep telling my daughter about: dictionaries.
There is no shame in using the dictionary every time you see or hear a word that you are not sure of. Not only does this reforge your vocabulary, it also enhances your hearing skills. It's important to pick up the correct spelling just from hearing once, and recall the correct meaning. Use a dictionary every day, at that moment. When you use it thrice or more a day, you will see a huge difference in your learning speed, and you will wonder how you were learning without this good habit.
As I mentioned earlier, listening to the word is important too. Reading is not enough. Which is why I recommend thefreedictionary.com as the best dictionary to use online. Even the home page has an interesting "spelling bee" corner which is challenging. I use it whenever I'm online, because of the audio pronunciation at two different accents.
However, most of the time at school, without internet connection, or a laptop, I use this android application to find the exact pronunciation. It's advantages comparing to browsing the internet are: being fast, offline, having a vast variety of words than other android dictionaries, example sentences, optimal color contrast, and a few synonyms present. It also has audio pronunciation and other Latin-based languages. Being only 15MB, it's an offer not to lose.
It may be spring break for my students, but the journey of learning never temporarily pauses. Keep Learning English!