Icy, I've done a fair amount of music composition (including four semesters in college), and can offer a bit more general advice, mostly building on what both Bosk1 and Rumby have said:
-Get together with a couple of other musicians, and try pure improvisation. Don't fall back on cliches or your old bag of tricks.
-Step out of your comfort zone...force yourself to write in a style that's foreign to you. Experiment with writing melodies using serialism. Write a tango. Write a short chorale. Write a simple, pretty song. Write a country song.
-Listen to any sort of music you can...not to copy it or necessarily even be influenced by it, but to expand your consciousness and your music sense.
-At this stage of the game, don't worry about being perfect, or writing your defining magnum opus...this is your opportunity to grow, explore, and stumble on your own unique voice & view...don't let perfectionism stifle it.
-Put it all out there, even if you think what you're doing may seems stupid, simple, or odd.
-Trust the process.
-be motivated, but try to relax.
-Listen to criticism, but don't listen to criticism.
Hope that helps.