Well, that's the hard question that everybody is having a hard time answering, even the seasoned users in the market I may add. For me, I employ simple guides. (1) I try to study the project first, I take how much time they are planning to run the project before launching it. (2) I check on the forecast of the community about it; will its coin be launched well and be widely embraced by people, or would it be a one trick pony that will not amount to something more as when it is first launched? (3) I also try to check its background, its white page, together with details about its developers and managements team, if they have launched many projects that found success, then that's a good sign. If the management team is a trustworthy one, then that would also be a controlling factor. To sum up, I think you should try to check for everything, and if it turns out good, at least on paper, then that can be a reason for your to invest in it.