I think at this time it's a lottery. Since it happens that the excellent company is a scam and vice versa. Of course, you need to study everything and everything, but it still will not give one hundred guarantees.
Guarantees that you do not fall into the swindle you will not give anyone, but to minimize the risk is quite realistic, if you carefully study the project before investing in it. You can not rely on the first impression of a superficial acquaintance with the project. Only in-depth analysis will help you choose the most promising project.