Keeping a sketchpad is an important part of learning to draw and paint. It is a place where you can sketch, develop ideas and collect inspiration.
Some beginners in art feel that artists go from observing to creating a final piece of work, just like that. This is very rarely the case, artists use sketchpads for preliminary studies, rough notes, doodles, tonal scales, thumbnails and ideas. I use my sketchpad as part scrapbook and I stick all sorts of inspirational images inside. I also try out media in my sketchpad, for example layering paint, scratching into layered paint, painting onto new surfaces and anything else that I fancy trying.