If you play a musical instrument, you have to develop a coordination for rhythm and a faculty for hearing the way notes work together in melody and harmony. Part of it is developing your ear and you have to go through some training before you can do it. All the great composers were also performers like Bach, Mozart and Beethoven, even the Beatles otherwise they wouldn't have had such sophisticated ideas and be remembered today.
I deal with people who expect to be professional musicians all the time, but they think all they need to do is own equipment and they're set. I can just see when I'm with them that they don't have those faculties for rhythm or melody.
So I advise anybody to either buy a book to learn from or have some lessons in your chosen instrument and do your practise. If in doubt, the keyboard is a good instrument to choose because...
