Impossible to do.
If we talk volume, we have the group of people who swear by it, and those who say its useless. We can further break this down by instrument, where for one instrument its completely useless, like spot currencies, and for others, like futures, it all depends on the trader.
I've been at this game long enough to know that many things in trading can work, even though some might not know how to use it, and also that nothing works with a very high degree of confidence. So to me, having an argument about what works and what doesn't isn't the right type of argument. Just like some people say that anything below a 1 minute chart is noise, while others feel that every tick is important.
About all you can do is ask the person to show how they use whatever it is that they say works, and see if there is any statistically significant edge to what they are saying. For example, with regards to volume, I've seen breakouts on high volume fail, and I've seen breakouts on low volume continue, so volume to me isn't that important. But if someone would show how they use it, I might be impressed, or at the very least concede that it has value for them.
But for someone, especially new, its impossible to distinguish signal from the noise. Until someone shows how they apply whatever it is that they are raving about, and shows the results, there really is no way to say what is signal and what is noise.