Definitely the key is you, and your way of learning. everyone reacts differently to different ways of learning, and one of the biggest failing of most eduction systems, is the ridiculous belief that everyone can learn the same way. So each person needs to find their optimum learning methond.
The first biggest mistake you have already made though is assuming there are two ways to learn, there are many ways to learn NAV, not two. So be creative and check what other options are out there. For me the best learning method is teaching and doing. If you teach someone to do somethign, then you learn yourself how to do it very well. But doing is even better, I set my self a project and tackle it start to end.
When I first started in Navision, my job was to train users to use the system, so I got all the manuals and read them cover to cover. then I started using th esystem to do the jobs that they would do in their normal day, then I sat down and taught them. this was all done in Test Company (before the Cronus days) and I learnt what posted where, because during training the users would ask me.
Of course some people are not comfortable in front of an audience so teaching just makes them nervous and they don’t learn. Some people are ver impatient, and so don’t want to create a whole project from start to end. Some people don’t want to go at classroom pace, so they get distracted. Others don’t like reading and can’t remember that way.
My advise is to try a bit of everything, and see what works best for you. For example I don’t really like classroom training if it is rigidly following the book, i.e. the “teacher” at the front of the class is just reading form a book, others I know hate it when the teacher goes off track and does not folllow the book exactly. So even with in classroom training there are different styles. For me classroom works best if there is a specific issue I don’t underrstand and that is covered in a classroom.
An example, when I moved from DOS to Windows, I could get most concepts clearly, except menus, they just did not makes sense. Try as I might I could not get a new menu working, so I was running all my new code from the object designer. Well I went to the DOS/Windows crossover course, and the first topic on the class was Navision Financials Menus Form330. Ten minutes into the course I was able to create menues and I was happy. Such a stupid thing. (Actually the really great thing was being told that in codeunit 1 was a line that said Form330.RUN).
I really do suggest that you attend a class, but not yet! Learn a bit on your own, then once you have an idea of what you need to learn, THEN go to the class, this way you can decide what is YOUR best way to learn.
Oh what I will say though is no matter what the very very first step to learnign NAV, is to post items on a sales order to an invoice, and pay the invoice and track all the entries created in NAV. That is step one.
Good luck.