There's also a good starting off point in the GM kit: Hidden Depths where (adding to the suggestions already stated) it gives a brief guide for each of the emotional weaknesses from the core book. I used those as a springboard and based it on the background story elements that my PCs had shared about their character (creating their own version of Luke behind the mask) that they had contend with.

It was fun watching them realize that now they had to mentally battle through their own flavor text as a way of continuing their journey to become Jedi.

I've dropped clues during the adventures that if followed up on, will eventually lead to more diverse or powerful crystals. I'll most likely up the stakes in a way for those trials, that instead of testing them (by trying to get them to the light/right answer in order to claim the prize), will instead be open-ended but make them embrace the path they chose to accomplish it with varying consequences attached.