1. Research and Reviews: Check supplier ratings and reviews on platforms like Alibaba, Oberlo, or Spocket to assess reliability and product quality. 2. Sample Orders: Place sample orders to evaluate the product quality, packaging, and shipping times firsthand. 3. Communication and Responsiveness: Assess the supplier's communication skills and responsiveness, as good communication is key for handling orders and resolving issues. 4. Certifications and Compliance: Ensure the supplier complies with industry standards and has the necessary certifications, especially for specialized products.