Read their whitepaper!
Yeah. That simple. You look at how unique their project is and how the community would benefit from it. Then next is the team behind it which is really important if they're legit or not. And you can add a little bit of extra research about it.
to find out whether the coin that we choose either live to see development graphics on the market. because with a coin that has an improved graphic it is a very reliable coin for the future. so it would be great to have an increased coin and can generate such huge profits.
You can find someone easily who can write whitepaper very well for quite amount of money! whitepaper doesn't guarantee that the coins are good or not but the progress of the project is the most important thing.
I must say that I put progress above everything else, whitepaper is just an ebook, but progress is a real thing!