There are a couple of things that me and some friends do:

 - check several rating sites to see which ICOs appear more in the 1st spots
 - check youtube for references about those ICOs
 - Check roadmap

Conclusions and made based on a good review from several rating sites, after some youtubers and opinion makers state if the ICOs is good or not. This is very important because it creates hype to the ICO and that can make it rise in popularity, aka, boost value upon release.

If a ICO is very popular, the devs will make more money, making it with less probability to disappear after some cash income, or before the ICO as ended.

Finally the roadmap. If it has a lending program, some investors will be tempted to hold the tokens/coins and invest more, like the beginning of Bitconnect or Davor.

Now, the most important thing. ICO are all scams, so you need to know when to take your money out!! You need to check for signals and withdraw your profit.