This is a subjective matter because not everyone has the same preferences.

Some might only base on what they're showing on their social media channels. Some might only be basing on what they're sharing online. Some might base on how good they are at spreading information. I mean there are other things as well that other aspiring traders can use as a preference.

As for me, I only look at one thing, and that's how good he is at sharing knowledge. I mean you will see if a "mentor" is really a good mentor or not based on the things that he/she is sharing on their own platform. There are some that are only sharing information that can easily be researched online, but there are some that are sharing some strategies as well that could help newbie traders and the best part is that, some of them are giving it for free which is a good start for those aspiring traders out there.