Reading books

Try reading books, in English of course, this way you're going to see how words are written. When you do this, try understanding complete sentences or paragraphs, do it with a dictionary, so if you don't know the meaning of a word you look for it inmmediatly for understand what the text is saying and for learn a new word's meaning. You could also have a paper, and go writting down there the new words you learned and its meaning in Spanish.

Some good ideas are to try reading the book in Spanish even if it's written in English, so you will be proving your level of vocabulary and how much you can understand, and when you can't understand something you look for it in the dictionary, but don't do it without it just in case you need to look for a word.