How do you find reliable overseas manufacturing partners as a small e-commerce brand?

I've spent time on the sourcing side of e-commerce (based in Hangzhou, working with electronics manufacturers), and I'm curious how founders on the buying side actually vet new suppliers before committing.

A few things I'd love to hear from this community:

• What due diligence do you do before trusting a new factory/supplier you've never worked with?

• Have you ever gotten burned by a supplier, and what red flags did you miss in hindsight?

• Do you prefer working through platforms (Alibaba, trade shows) or building direct relationships?

I've seen this from the supplier side, so I'm interested in the buyer's perspective what actually builds trust for you when sourcing internationally?