One of the best tips I think I can give beyond learning various techniques and the basics to watercolor painting is to paint what you love. If you love what you are doing and you do what you love you will constantly continue to improve. If you love landscapes, paint landscapes. If you love barns and farms, then paint barns and farms. If you absolutely love flowers, paint flowers. Keep painting the subject matter you love. Inspiration to paint will come from those things around you that you treasure. What better way to keep practicing than to paint those things you truly love to paint.