Make it easy on yourself at first. Most popular American writers, fiction and non-fiction, have been translated into Spanish. Choose something you’ve already read. Maybe Los siete habitos de la gente altamente efectiva, by Stephen Covey, or La firma, by John Grisham.
Reading is the easiest of the four skills of language. Why? No pressure to indicate you’ve understood, no pressure to understand, all the time in the world to puzzle it out, similarity of many English words or roots and stems, context to help you. It’s one of the two passive skills, but, in contrast to listening, where you usually have a real need to understand, reading is much less demanding.
Also, take advantage of the opportunity all around you to read something in Spanish. Waiting at the Department of Motor Vehicles (or any government agency), you can read their bulletins in Spanish. Directions for every new lamp or toaster you buy will be in English and Spanish. Pick up People en español at the grocery store checkout.
The ability to read well is a skill in itself. It is transferable from one language to another. If you’re a good reader in English, you’ll be good in Spanish too.