Personally, I have participated in ICOs because of the uniqueness of a project as well as the low marketcap and price that's usually being offered during an ICO.

The most important thing to do is to do your own research, additionally to watching available researches of projects you are looking into! Check for information regarding the company, team (experience), community, developers, and if the team attends events to spread their word and performs good marketing efforts.

Personally, I enjoy watching Scrembo Paul, you can find one of his ICO reviews here: https://www.youtube.com/watch?v=eCVBYBssLS8