One of the most important things are the whitepapers regarding the cryptocoin.
They should be publicly available some time before the release of the coin so they can be revised by the peers.

Also make sure to check and see if the purpouse of the coin has some sense and if it can be applied.

Be wary of "you will have credit cards linked to your coin wallet", this is probably one of the biggest red flags. It hasnt happened with any other coin so it wont happen with a new one.

Anyhow if a coin gets into you try not to put all your money into it, just take it as a high risk investment.