I work on rhythm first and then build up from there, since that's going to be the bit that people are boogieing to. Although I don't do much in the way of lead lines, I tend to explore the dynamics and harmonics of the mixed rhythm, textures, pads and lines, see what comes out, it's normally really slight riffs in odd frequency ranges and sounds which aren't intentionally there, some vocal like others very organic. I also explore getting the sequencer to do desyncronised loops and to make pitch/timing decisions for me, giving the tracks even more a life of their own.

But then again if you want a track that's popular, don't do what I do ;)