Definitely avoid the forums if you do not want secrets ruined, there's so many casual spoilers here.
Simply doing your job and exploring and playing with all the toys in the shop and world in your off time will get you most of the interesting secrets and events- there is a huge amount of easter eggs that you likely won't find without SOME internet browsing but they are mostly easter eggs/silly memes and references, nothing important. The only tip I would give you for weird secrets you can figure out yourself but need a pointer for even thinking to try is that the tutorial is bigger than you think.