If you can discover what it is that you really love, and then put your soul into doing that as best as you can, to me that is the seed of real success.
Develop your soft skills as much as your audio skills. You can be the best sound designer in the world, but if you can’t write a coherent email, show up on time or behave in a humble and professional manner, you will have a hard time building your career.
Be mentally ready for changes, respect your own internal clock and sense of integrity. Be kind to those who deserve it and protect yourself from those who would abuse your talent and dedication in the name of personal gain.
Don't be afraid to spend 6-8 hours a day on your computer to learn and to write your own music. I know that it's hard when you already have a job but if you work hard, you give yourself better opportunities to succeed.