Any invest in ICO take risk, especially if this doesn´t supported or not have time at the market. I meet people who invested more than 5 BTC in new ICO project and loss their investments, I know is a difficult to talk about it, because it´s about our own investment. This day i look for good new ICOs projects (previous analysis of each one) and decided to invest in these, I would like to have a reference about how much money normally your invest in a new project? 
I dont think anyone out there will tell exactly how much you should risk with ICO. My advice for you is take risk according to your nature to risk. Even if you do all the due diligence and confirm that the ICO is genuine then all of a sudden the Project owner run away with all the money like (Extoke)project or maybe the crew start to fight among themselves like ( Envion) project. Then you will still lose your money. So pls my advice is to only invest what you can afford to loss.