I base it on a few factors....must have a whitepaper with detailed information about their mission, the website needs to be more professional looking, they aren't making growth claims (ie...buy for .05, will go to .75), and people have mentioned them in a social feed. This worked for me when getting into the Dragonchain (DRGN) ICO, for example.  Also, looking at Bob's Repair, which, from my perspective only, looks interesting on their upcoming ICO.  Good luck out there and never invest more than you are comfortable losing.