The first thing I would suggest is going to their website and looking at their development team. You should see a picture and a REAL name to go along with it. If their website lacks leadership information then consider it a red flag, you do not want to invest in an anonymous team...
Once you do find them, search for them online everywhere... find their LinkedIn and see what level of credentials they have, what have they worked on and what have they accomplished? Who are their partners? Have they worked together in the past? Etc, etc, etc. Perform as much research on them as you can, youre not just investing into the coins technology
Youre investing in the team.
Also, read the whitepaper. Here you will find out all of the information on the companies plan for what theyre trying to accomplish, how they will use the money, how many coins their team will hold for themselves, and more. Try to make sure the company isnt too overly optimistic about their goals and visions, as this may raise a red flag as well. The whitepaper may be a boring read, but it is necessary to do.
Another thing you can do is read the ANN thread on Bitcoin Forum - Index. This is just a message board where people discuss cryptocurrencies.
There is a good trick you can use when searching for ICOs on the message board, and that is to search the name of the ICO with other terms such as scam or con along with them.
If a post is flagged with these terms you can read into why it is.