Because the various topics, industries and organizations you'll be focusing on cover a variety of fields, a broad, interdisciplinary database is a good place to begin searching for scholarly articles. Remember that many of the following databases include BOTH scholarly and non-scholarly (newspapers, trade magazines, and other popular periodicals) sources.
Reference sources (encyclopedias, handbooks, almanacs, etc.) are good for finding background and overview information on a topic. Listed below are large gateways that include various subject-specific reference materials.