Two of my favorite themes are birds and trees. I think I like birds so much because of their freedom, their lightness of foot, lightheartedness, and because it would be fun to fly! Trees are always dignified and unflappable and represent slow steady growth.
Painting to me is the opposite of drawing in many ways. It's spontaneous and experimental. You get to play with the flatness or sculptural quality of the canvas. And best of all you get to make a mess. I love getting all my materials out, experimenting with this and that and when I've made something I'm happy with I clean it all up to start over fresh with a new idea.