For the Representational Abstraction landscapes, I typically work by doing a plein air study. Some of these eventually turn into finished pieces. Often, I create a larger version of the study in my studio.
Most start being quiter representational, but then each painting takes on a life of it's own. I really have no idea where a painting will end up when I begin it, although I suppose I have some sort of dimly defined image in my mind. At some point, I'm not in charge any more - the painting takes over. Some works remain pretty representational; others get quite abstract. They gets worked and reworked until they looks 'right,' whatever that final form may turn out to be. I don't work well in watercolor for that reason - to me, with watercolor you have to know pretty much where you want to end up before you start.
What I try to do in my paintings is to capture the essence of what is depicted, a distillation that I also strive to make pleasing to the eye in terms of form and color and texture. The paintings are thus 'abstractions,' but are also referential - almost always grounded in life, mostly in nature.
The concept for the mostly larger abstact expressionis pieces seems to come to me just before waking up. I;m not sure where they float up from, but the challenge is often to retain the idea when fully awake!