1. Choose an ICO with a lot of activity - You can see it on their facebook page or twitter. Look if the company joins a lot of conference and things that can promote their coin.
2. Choose an ICO with an admin that responds quickly - We all have some specific questions and corrections that
needs to be made and an admin that responds quickly for every question is a plus.
3. Look for the one that reached their soft cap - If an ICO reached its soft cap then its a high chance that it will be successful.
These are the basic things that I am looking when joining a bounty to avoid scam. If you have other ways then feel free to share.