A solid product with a experienced team behind are good signs. If they are transparent and they have a long lasting history and background it means that they do know what they are doing and probably they will not fail 2 months later. A good looking website and a well-written whitepaper are a big plus. Also be carefully how their token model is. There should be an solid link between the tokens they are issuing and the product they launch. Without it, the tokens that you might get from them are worthless.
If you have any questions or you have found any red flag do not hesitate to point it out on their community channels.