It's really a matter of which aspect of Bitcoin you want to understand.
I would recommend getting a feel for the overall nature of Bitcoin, then proceeding to whichever area tickles your fancy. You could look more into the blockchain, transactions, or encryption / digital signatures / hashes.
The forums here are also a good resource if you have any narrow questions (using the search function first is recommended since almost every conceivable question has been answered a dozen times before).