You have to take a lot of reading and research. The first thing to do is to check the white paper, the most important part of it is the development team. Be sure that it stated the personal information about them and if they a real people. Check out the background and see wether they really made a previous project. Second would be, the technology behind the project. See to it hoq it work and if the timeframe is realistic.

You should also check some reviews about it, and wether influential people are getting themselves engage with it. Most importantly, you should have a background knowledge about the project. Be sure you really knoe why you are  buying.