- Don't trust someone fully, especially when he gains something from you.
- Always appeals to greed (or vanity or fears).
- Claims it's risk-free.
- Dismisses your objections too easily.
- If it's too good to be true, it is!
- If it was really a great way to make money, why is he telling it to you?
- If he claims to have insider or special or secret knowledge.
- Does he try to find out personal things about you, that have nothing to do with the business? (I.e. probing for your weaknesses, your fears, etc)
Business is business, don't let sentimentalism get in the way.
Nobody owes you a living and it works the other way round too: you don't owe anyone a living too.
Ultimately, you are responsible for your decisions, let your yes be a yes and your no be a no. Not a maybe, not an okay lah.