i am not very good with the creative process, sp i picked up a tip from my homie, he said, find the hook for a song you wrote, a melodic one that involves singing or just very distinct notes, find a sound you like, then make the notes match, this sound will only play for the hook, then take a different sound, take some random notes from yur hook melody, and use these as the verse, or you can make somthing tatally new that fits, whatever is easier, then from there, make a bassline that fits it, im usually pretty good at taking a beat and making the bassline in my head, then sit and beat box to it, thats how i usually do the drums, i beat box a lil to the beat, find what sounds tight, and recreate it into the beat.
when i just go completely off my creativity and no song, i get a melody in my head, it is usually not clearly and instrument, i try couple sounds, see what works best with it, then build from there