Good question, for me this is what I look for when I do my own investigation,
a. whitepaper - is it original? or just another project can copy others?
Some scammers are always in a haste, since they know that they have no long term vision, they do things hastily in order to scam fast and move on to the next project. That is why you see whitepaper plagerism.
c. tokenomics - how it the tokens distributed, will the majority of the stakes are going to the devs themselves?
Is this information always public? Can't they be doing another thing behind the scene and present another to the public.
d. where they are going to list? Is it on a top tier exchanges or just fly by night?
A nice research point. If reputable exchanges have accepted and bought some of their presale coins, a good sign right?
e. what kind of marketing are they going to do? shills? bounties here? or getting a good bounty managers? funds escrows?
If they choose shilling and bounty, is it a red flag?