Do our own research about ICO. Reading the ICO's whitepaper is a must. Also keep in touch with ICO's website and their social media pages like facebook,twitter,medium. Also getting ideas and opinions from crypto experts will also help in great amount.
Good advice and i may add also to read some ico review sites. I am also using cointelegraph, newsbtc, ico rating, icobench and so forth. More sources means narrowing your choices and filtering only good ICO's or lowering your chances to be scam. Always do your own research and always guard your investment from scams.