I guess it's similar to any other investment you might consider, so obviously you should be convinced by the project - check if the idea makes sense in the long-run and if it's actually feasible. In the next step, try to look for transparency. Most likely, not all information will be published (if that is the case, i.e. too much information and/or confidential data is published, be careful I'd say!), so look for a good team and advisors and if it's transparent. It's good if you find advisors who were already part of other successful ICOs. These are the most important points at first glance in my opinion.