There's really no assurance when it comes to investing in ICO. But there are some factors to consider to at least won't lose you investment. Make sure that the people working behind the project specially the campaign and bounty managers managing the ICO are reputable. You need to see to it that their website do have good design that has real effort that they put into it. Most scam ICOs have shitty whitepaper and websites. Research on the devs that are working with the project and always try to see to it that there are huge number of people participating in the ICO.