For me, writing will be spontaneous, I can't force myself to write, no matter what. Sometimes I'll get an idea, then forget it for 6 months before continuing. dialyn is right, there is no single or best way to write, you just have to use your imagination and the time that you have. Writing when not in the mood to write will just be detrimental.

"Walk down the right back alley in Sin City, and you can find anything."