Sometimes I just sit and play a note once, twice, thrice, over and over again. It's almost a form of meditation. Sometimes I let the note ring, sometimes I hold the pedal down till it fades away into silence. Sometimes I cut it short, forcefully, in a vindictive staccato. Like I should have let it be but I didn't.
Only recently I've been playing something that is slightly close to what I wish to express. This reproduction from the inside to the outside (both while playing music and writing) is a somewhat tricky issue. Experimenting with Buckley's Hallelujah, I was surprised, and rather pleasantly so, to find that I play completely different chords when in different moods. Try to play what's in your head, then forget the head, and the expression is all right.
Writing, in many ways, is like playing the piano. Or vice versa. There are no incorrect sequences or combinations of words. Throw in a bunch of random chords and make them talk. You forget the rules and trust the sound.