Your best education

People that work in marketing usually gains a common habit. Over time, you can see which ones have developed it more because they get promoted in their careers. I’m talking about a skill that if you make it an habit you’ll become better at your craft. It’s observation.
Marketing is about noticing things and point them out. Whether you want it or not, when you become a marketer you change the way you see the world. Like when you’re watching a movie, you immediately notice everything. 
Whenever you’re out there, you’re constantly observing how people behave, it’s just an habit you gain. Observing how people interact with a device in real time is your best insight. Sure, user tests work, but they will never be a real interaction.
Maybe you’re not observing how they use your product, but you can get a great insight of how they use a platform. And that’s valuable knowledge for your product, however. This is so simple that not everybody is aware to notice things.
Your best education is out there, for free. You’ve got to gain the habit of observing and asking questions. And this applies to more fields than just marketing.