Listen to everything around you and memorize the sounds of the physical world. Always have a recorder and camera with you. Think about how and why things behave the way they do. And you better really like putting in long hours, because you're going to be putting in some really fucking long hours if you want to make sound and music for a living.
Keep going, and don't stop. There are SO many talented people out there and I see so many of them give up over time. No matter what it is, composing, running, flying - keep doing it and you will eventually succeed. That is literally the only one thing that you need in order to succeed - just perseverance.
Don´t ever give up and take it seriously if you really want to be successful on this. Networking is a really important but do not act like a jerk. I already know cases of people that are trying to start in the business but their names are already in the “black list” of fellow composers and professionals of the industry.