Before I start, the best tip I have for you regarding ICO's is that every ICO is a scam until you prove you're self differently, only when you 100% sure you can start thinking of investing, and there is a lot of great projects out there.
1- READ THE WHITE PAPER! you have to understand what this project all about, read it all and read it under consideration
2- Telegram, If it active and have a lot of traffic and strong commentary Its a defiantly a good sign
3- The company tech team. The tech team should be with experience and knowledge relevant to the project, remember the engineers are what motor the idea, without a good tech team even the most amazing idea will collapse, example :
4- PR team- PR is one of the most important parameters when you look at ICO team, even if the idea is great without the right audience to acknowledge it and exposure it won't be able to make it, for more regarding this subject the- HERE
5- Compare the ICO to competitors-A thorough analysis of existing competitors to gauge if there are similar products or solutions in the current market. If so, identify the salient features of this project that are likely to beat out the competition that exists.