Ask HN: What traps to avoid when dealing with offshore partners?

I am a US-based entrepreneur who is considering partnering with an offshore hacker -I never met face-2-face- residing in the EU.The deal would involve a fixed payment plus equity/profit share. What are the potential legal issues to avoid? Are NDAs and partnership documents enforceable across borders? Is it worth it or shall I stick with local hackers? Any recommendations for background checks in EU?