how do you do it? my stuff, i sit in my bedroom, take that riff or two to practise, have my drummer make up a line, then me and him write keys and guitar parts
I don't really have a system, I just seem to randomly make things up that end up sounding good in my head. I usually just write lyrics, with a theoretical tune in my head. Then, I go home and make up a bass line and maybe a guitar part (for some reason, inspiration always strikes while I'm half-asleep first period ).
i don't really have a system either. but i found that it is usually one of these ways 1.) i'll be sitting and start drumming or humming and i get an idea i like in my head and keep it playing in my head until i get to a bass and can put it on it. but it usually nevers sounds like what i heard, but i like it better. 2.) when i'm playing around on the bass i might by chance play something cool, but the hard part is remembering it 3.) this is the rare one, i'll get a weird sound in my head and then play around on the bass till i get that weird stuff, some of the things i've done are pretty out there. but this is just me, i really like to work to chords, but a cool bass riff is always fun -jimbo
I don't do it much nowadays, but when I was systematically writing songs I would always start by programming a drum part and then build up everything from there.
here is something which I found interesting, and rather helpful too. http://www.bassplayer.com/artists/freemind.shtml