Actually it's very difficult to predict so.. there are lots of good ICO and already finished ones that have a great potential but market is very hard nowadays. I think you have to be lucky too...
I agree with your statement it is really hard, on my part i'm looking for new project to add signature campaign but there are lots of choices both have great platform but the problem is do they really are a great? Because at the end of the day we don't know who's project will skyrocket in the crypto market.
It is very easy to hype people by making great graphics, information on thread like ANN as well as creating an attractive official website to catch our attention but we don't really know who among them are honest projects.
Hmmm, we can only join 1 signature campaign and we have to choose the best project that worth our time and effort! Some of my friends who also are bounty hunters are joining almost all of the projects, joining lots of projects but it is really hard to manage!