of course a good investor will first do its own research (whitepaper, roadmap and etc), besides that what is your biggest motivation?
Every person has their own method to try to find good coins in my case I give a huge importance to the developers, the white paper and the roadmap are important but if the developers are not able to realize all of those ideas put in paper then the project is not going to become successful, you need to check the credentials of the developers and see if they are real because if they are not then most likely you are looking at a scam.