Effective SEM campaigns require understanding business objectives, defining target audiences, optimizing ad campaigns, and tracking performance. The key steps are understanding the business, setting advertising goals, targeting the right audiences, setting up campaign structures and keywords, optimizing ads through testing and adjustments, and regularly reporting and analyzing campaign metrics and ROI. Landing pages should be optimized for usability and relevance. Regular reviews ensure adherence to best practices for search networks, content networks, devices, and channels.