One of the best things you can do to improve your Spanish skills in less time is reading a book series. Ideally, it would be a series you’ve already read in a language you know (i.e. in English). If you are a fan of Harry Potter or Games of Thrones, you should probably go over them again in Spanish. As you already know the plot, the characters —and you enjoy the books— your learning gains will be accelerated at a low cost.
Another option would be to pick a series you haven’t ever read, written originally in Spanish. That’s exactly what I did one month ago to get better at Italian. Searching for Italian novels on Amazon, I came up with Federico Maria Rivalta, an author who writes crime stories. I was delighted to see he had a series of… 11 books! I’m on the fourth volume now, and I intend to complete the whole series. You can do the same in Spanish! There are plenty of authors who write on all kinds of genres.
I like reading a series by the same author because of the consistency in style, phrases, and vocabulary that I find, over and over. If you enjoy one story, chances are that you’re going to find the others equally appealing. By getting into the fictional worlds created by a writer, you will repeatedly encounter a set of specific language expressions. And that’s a good thing!
What’s your favorite book series in Spanish (other than the Spanish Novels by Paco Ardit, of course ?)?