First things first, you should do your assessment, due diligence of the person offering you this opportunity and the assessment of the offer and underlying business model.

Do you know this person, do you have an established trusting relationship?
Does this person have successful and verifiable business traction in the same field?
Are there any references you can check?

Also, assess what you could do alternatively with the capital that you would invest here? A comparison of the opportunities' type, risk profile, ROI etc will make it easier to decide if this is even a relevant opportunity for you or not.