You can keep a small sketchbook, pencils and an eraser in a backpack, or in the car, and sketch scenes you see, places you visit, or things you imagine. These drawings can be developed in more detail later on, or simply stand as a record of your ideas and experiences.
Sketchbooks keep your work neat and organized, whereas loose papers tend to get lost or discarded. If you don't own a sketchbook, you can make a simple one by stapling together a small stack of recycled white paper. You can even make covers for your book, by using colored papers for the top and bottom of your stapled stack. Keep drawing...