A few days ago I said that reading was the key to improving vocabulary. Many people assume that means you have to read literature or technical manuals. While those are both good options, if you find them boring, you will not continue reading.
If you have a shorter attention span, improve your English vocabulary through an interesting website. One site that I personally love is Lifehacker. This site has everything from interesting apps to ways to improve your relationships. It is all in English, so you can improve your language skills while learning interesting life tips.