yeh i know that feeling..
the times when I know that I'll churn out something I like is either:
- I imagine something in my head ( before Im at the keys or puter ) and then I go to it and try and put it down
OR
- Im seriously stressed out, angry, sad or something and I go and visit my 76key therapist.. then it just flows..
..I also have sat down and said "ok I think i'll make a song now" and whatever I come up with is just damn ugly..never works for me
Thats for the main song structure/melody.. the effects and everything else I get the conventional way.. like "i'd like an effect like that there.. so lets make it"
Thats what I've found anyway.
PS. All quotes go on in my head.. not out my mouth.