First and foremost, does it solve a problem? If yes, is the problem that it solves significant? If yes, are there any other similar coins? What does this one do better? From here I check the whitepaper, research everyone on their development team, look at their road map and look into discussions involving the coin on forums like this. If you're in it purely for profit, it's good to make sure the market cap / circulating supply aren't too high either.