Begin by browsing our Drills section and keep checking back. There are a bunch of great TGM drills that haven't been put up yet.
I can think of a few off the top, but I'll save it for your questions in the Drills room!
You are right about Lag, it is the key and the "secret" of good golf. Preparing it, aiming it, thrusting it, and sustaining it is what it is all about.
The best way to start is right here. Read and absorb. Ask questions. Read the book, and apply what you are learning.
It doesn't take long to take ownership of your swing!