Painting is always a surprise. Even when I have a specific subject or message in mind, even when I have a fairly clear plan for the composition of my picture--as in NAFTA: No Mas or Ghosts of Guantanamo, governed as they are by straight lines laid down with a ruler--there is plenty of room for mucking around, letting the brush have its way. I don't like the lines to be too straight; I like thick and thin, sharp and ragged, nothing too settled, too precise.
I court accident, try to be alert to chance effects that arise as strokes cross one another, overlap, blend with other strokes, skim the surface, leave gaps, end abruptly, or fall away. I use brush and palette knife. I like the palette knife, the way it can be assertive-- overriding or obliterating existing forms--but also the way it drags over surfaces and breaks off, leaving unexpected shapes and allowing underlying color to suddenly peek through.
A voyage of discovery, you might say? There is much to be learned in the process of painting, much to be discovered about one's subject and one's self. Even when my content is sure and my design determined, I try to let discovery be my guide.