I bring a sketch pad with me whenever I travel on the weekend so I can sketch flowers if I find a nice garden. I have a small sketch pad 5″ x 7″ that I use a flair type pen and then I add a watercolor wash to the pen drawing. Besides being fun it is great practice and will improve your drawing and observation skills.
The sketch on the left was done on acid free foam board. I like foam board because it is light weight but stiff enough for painting on without any support underneath. I first made a sketch in pencil and then painted in watercolor. I added a bumble bee because there were several flying around the flowers.
Sketching is also good for previewing compositions for a more detailed painting done later, either on location or in your studio.