There are so many data that you should study before buying an ICO...the quality of the team and the real utility of the products are the first two points yous should focus on...but these two factors alone are not enough to tell you if this kind of investment will give you good profits...
Token metrics is also very important..for instance if there have been a private sale with a huge bonus/discount for investors this is a red flag if you are going to buy during a public pre-sale or crowdsale..because those who have bought at a lower price will dump their tokens once the project is listed on an exchange and this will cause a substantial loss in terms of the value of the token...
So my final advice is to focus on the quality of team and project and on the token metrics.