Generate a detailed 500-word article outlining a comprehensive client onboarding workflow for a SaaS business.  The workflow should focus on minimizing friction and maximizing client success.  Consider the following stages: pre-onboarding (pre-sale communication and preparation), initial onboarding (account setup, initial training, and first contact), ongoing onboarding (ongoing support, feature utilization, and relationship building), and offboarding (client churn prevention and data archiving).  For each stage, specify actionable steps, key performance indicators (KPIs), tools and technologies that can be used to automate or streamline processes, and potential challenges and solutions.  The article should target SaaS companies with a focus on improving customer satisfaction and reducing churn.  Include specific examples of email templates, onboarding checklists, and knowledge base articles.  The tone should be practical and actionable, focusing on delivering clear, concise instructions and best practices. The final output should be structured with clear headings and subheadings, making it easy for SaaS business owners to understand and implement.  Measure success by the clarity, comprehensiveness, and actionability of the provided workflow. A successful workflow should reduce the time spent on onboarding, increase customer satisfaction scores, and decrease customer churn.