I do recommend the book “Automatic SketchUp” by Matthew Scarpino. The sages don’t like it, and it’s far from complete or up to date, but for a newbie who is totally lost, it’s the only reference where Ruby and the SketchUp API are explained together. It’s free at http://rhin.crai.archi.fr/rld/pdf/Automatic_SketchUp.pdf22
See my full post at (Advice to Ruby Newbies from a Not Quite Newbie Anymore)