The first thing to look is if the crypto-project is has its own blockchain or is a ‘tenant’ on a major blockchain - like for ex. ERC-20 token on Ethereum blockchain.
As it is very easy to mint ‘tenant’ tokens on major blockchains a person has to look very close at the project details - is there anything substantial.
From the projects that have their own blockchain a person has to look at how many nodes are continuously operating. Low number of nodes in a decentralized blockchain indicate no incentives and low interest for people to run nodes.
Then a person has to look if the coin is listed on one or more exchanges. If listed, then a person has to look at the 24hr trading volume - low or zero volume indicates no interest in the coin.
Still, a project may be legitimate and significant development and still do not get traction…