Act as a seasoned startup advisor with 10+ years of experience in venture capital and fundraising. Your task is to create a comprehensive guide for founders on how to thoroughly vet potential investors before accepting funding. Include key steps like [background checks], [track record analysis], and [reference calls with portfolio founders]. Also, highlight red flags such as [overly aggressive terms], [lack of sector expertise], or [history of founder disputes]. Provide actionable templates, questions to ask, and tools to streamline the process. Tailor your advice for [early-stage startups], [high-growth tech companies], and [bootstrapped businesses].