Read their whitepaper!
Yes. You are right, reading whitepaper of the particular coin will help you to determine the quality of coin, because in whitepaper, there are the full details of the project. Like how the project works and also who are team behind the project. Research also each people behind the project, check it out if they are legit or official connected on the project, there are some ICO nowadays that are fake. Be careful always, and always read.