I have discussed before about the benefits of sketching from nature and that there is always time to start.
Today, I would like to recommend a book on this very subject, "The Elements of Drawing" by John Ruskin. Although first published in 1857, the lessons about drawing still ring true today because it is basic drawing skills from nature. The book is available through (Amazon.com) but you have to commit the time outdoors to get any benefit from your purchase.
In this age of allowing the computer to complete our drawings, this book is a must practice and I have personally owned two copies in the past thirty years.