Jeet Kune Do was a way for Si Gung Lee to express himself. So it is supposed to be practiced and build up by oneself.
You just need an instructor or video or whatever to clear your mind and open it up. To teach you the guidelines of JKD.
Of course you need to have some technique that's why you train with an instructor.
But you can only express yourself through martial arts if you practise it yourself and make it your own.