First, make sure to do everything in the village. It's basically the tutorial and teaches you pretty much everything. Probably takes 30-45 minutes.
After that? Go to the moon. Pretty sure they nudge you there from the village dialogue. It's small and pretty quick to see everything there is to do.
After that? Go wherever you want. The more you explore, specific things you'll want to do will become clearer. But the core of the gameplay is exploring and reading and learning about what's going on. You are never gated on power-ups since they don't exist, only by knowledge.