As the question reads. For me:
- The concept/vision - is it innovative? does it solve a real world problem? is the problem it solves something I am interested in?
- The team - Size and experience.
- How the coin relates to the concept. Is the coin a key part of the platform? Are other payment methods available to users, etc.
First is their concept, objectives, mission and vision to prove that their ICO will be success in the future. Second is their whitepaper, read the whitepaper from start to finish. Before I join in the ICO, I want to see the sincerity and integrity of the team. Then, third is the budget allocation and price. If the budget is big, the tokens you can earn is big. Be aware on the ICO scam.