Mark's book is the best if you can find a copy. As in the three videos he teaches the orthodox stroke. Without a repeatable, straight delivery of the cue stick accelerating thru the cue ball no amount of lessons regarding physics, strategy, drills, etc. will deliver optimum results. His teaching is the basis upon which everything else relies. Yes you can get incredibly good without an orthodox stroke, but it will take many years more to overcome poor technique. Lots of pros are evidence of that. But why make it harder than it already is?I think this book is great!
The biggest take away that will give the most improvement relatively quickly is the 'ladies and gentlemen' line. Watch that in the video.