maybe the factor that can make me believe with some of the existing projects is that I can read and see it from the whitepaper and after that look for certainty about the team behind the project in order to know that the person is genuine and not fake.
Along with the whitepaper , I see if I can visit them if they are situated in my country and meet and understand and get clarified all my doubts. It is important to have meeting if you are planning to invest money in any coin or PRE ICO .