If you do better in a course situation rather than learning from a book, I highly recommend the 3 online courses by Bjorn Meuris, a reader who has many years' experience teaching and reading Lenormand. He offers his courses on the Cartomancy University website where Caitlin Matthews also offers courses.
I had been working with the cards for a about 3 years but avoided the GT. I am not a professional reader and don't have a lot of opportunity to read for others so the practice has not been there, for me. The Beginners' course is set up in such a way that by following the exercises you cannot help but have the information firmly planted in mind.
If this course had been available when I first became captivated by these cards, I feel that I would have been catapulted into feeling like a competent reader almost as soon as I had the meanings drilled into my head by his basic course. He effectively creates a framework that makes it very easy to grasp the concepts of the GT that follows.
Going forward to the GT course, the way he presents the descriptions of location of the signifiers and theme cards with regard to the other card locations he rips away any doubts that it is possible, even easy to read the GT. With the way he tightly focuses on one element at a time makes the prospect of reading the cards this way, well, simple!
I highly recommend that any beginner -- or anyone who feels like they have hit a wall in their learning -- who wants to shorten their learning curve to take the opportunity of treating themselves to Bjorn Meuris' courses.
He has a beginner course, a GT course and a 'method of distance' course that applies to the GT. Every so often he has sales on the courses but they are still not all that expensive especially since they really shorten the time from baffled to competent.
The beginners course is here and the
Grand Tableau course is here.