I recently received the following email:
I'm a humble game composer from Russia.
What exactly were you doing while being a beginner? I mean, what activities are the most important for composer's education and development?
What I did as a beginner may or may not have any connection to what the typical composer needs to do to become educated or develop as a composer. From my earliest recollections I loved sound -- especially music. I found that I loved harmonies better than the melody. I just sort of knew how to harmonize. I sang a lot along with recordings and later with my younger brother who loved to sing melody as much or more than I loved to sing harmony.
A bit later, I took up several instruments. I never became an expert at any of them. They didn't play enough notes for what I heard in my head. Only a big band or orchestra had enough notes for that. But I played in bands and studied music theory in my head, learning chord structures (thanks mostly to guitar). I took songs apart and learned what each individual instrument was playing. This was tremendously helpful in developing a good ear. I got to be the guy in the band who wrote out all the chord changes. I got to where I could hear one instrument in a recording from the start of a song to the end. This came in handy when I started recording backtracks for singers (this was before karaoke).
Eventually, I started taking apart my favorite classical music, writing out the score just by listening to each individual instrument part. This meant that I go to know the piece inside out because I had to go through it over and over, layering a new part each time.
I also got involved in group singing, including Barbershop Quartets and choruses. This helped me develop an appreciation for how to balance the parts to best support the melody. It helped continue to develop my love for harmony, too.
All of the above was in the days before computers and non-linear audio editors. Being able to slow the tempo without affecting the pitch of the piece would have been wonderful, but it may have kept me from learning some of the lessons I did in listening to the pieces at tempo.
I have always loved a wide range of music. If it had emotion, I didn't care if it was classical, swing, pop, rock, world, whatever. All music with emotion has a lesson to teach. So I listened to all sorts of things to find music with emotion.
I've never taken a course in music composition, but I've taken many thousands of lessons. Listening to and playing with other musicians were some of the best lessons. Listening to music that was not run-of-the-mill included some other better lessons. Doing anything that stretched what I thought I could do was always a lesson, too.
Taking courses in music and composition probably would have decreased the learning curve for me. I think someone who wants to do something musical for a life's work can learn a lot from courses.
There is also a lot of information available on the internet. For classical music, an example is the interactive version of Rimsky-Korsakov's Principles of Orchestration -- available at http://www.northernsounds.com/forum/forumdisplay.php/77-Principles-of-Orchestration-On-line. This is thanks to Gary Garritan. All sorts of information on more modern musical styles is available all over the internet, with many video tutorials, too.
To me, the most important thing of all the above is developing a good ear and a good understanding of chord structures. These, along with learning music software will enable you to bring what you hear in your head to reality.
I hope this helps you in some way. Good luck in your creative endeavors!