I have been following this checklist:
1. Celebrity like profile picture
2. Proper name in username
3. Not common in any groups
4. First message from them is always a "hi/hello" without saying why they are contacting you.
You can be 100% sure that it is going to be a ponzi promoting scammer. I made it a point to no longer reply to any such users and block them right away. After a few months when I see by blocked list, I see most of them deleted their accounts.
Thanks for posting this though. Hoping some bamboozled newbie gets warned by this and does not fall for it.