The best way to avoid those scam is to go to those ICO that has already have an ICO in this way you can make sure that the ICO is not a scam or maybe you can be also a risk taker and in this way you can get a lot of profit but still there is a risk on it.
Or maybe better wait until the ICO is over, that way you can easily determine if the project is legit or not.
Mostly when a project generated a good amount of collection, they are most likely legit because investors trust them with their money.