in my own opinion, after you've checked the potential of the coin,website and whitepaper, you should also check out the impact of the project in your day to day activity. is the project about a paricular product? is it opened to other organization? it is very important you know that blockchain is yet to really get recognized by common people. when I say common, I mean inclusion of people that have less to do with internet.
There must be some level of potentiality in the sense that the project is opened to other projects and are willing to work with other crypto projects.Then most importantly,verify that they are really working on it and not just having printed materials and social media campaign without actually doing anything.