Most people would recommend:
1. Reading the whitepaper
2. Checking the professional profiles (LinkedIn) of the team
3. Checking social media for any relevant news
I have read also that large ICO % bonuses or very large overall bounty campaigns can be a sign that the ICO is a scam. If it looks too good to be true.....you know what they say.
Do you know any website doing good review on icos? At least it helps when doing reserch.