You may argue about topics like the trinity or hell, but the most you will get out of that is Bible verse ping pong with no one proving or winning anything. Trying to prove doctrine with a JW is weak game.
I have a few techniques I use for a study. One of them is to look up the verse that is cited in the text. Usually the first couple of them in an article are accurate enough, but deeper in you find that the verse has a very nebulous, if any, connection to what is being asserted by the writer. Point this out to them. Then ask for them to find a scripture that supports the claim, since obviously the one cited does not. The burden of proof is on them, since they came to you with fantastic claims. This can be lots of fun. One time one of them claimed the Nephilim in Genesis 6 that took on bodies to mate with human women abandoned the bodies when the flood came and went back to heaven. I said that was a fantastic claim, and asked if he could show me in scripture where that was so. Several minutes of silence followed as he leafed through Bible and cult literature. Finally he came up with Satan returning to heaven after wandering around on earth in the account in Job. Weak game indeed!
So it is best to not assert anything, be an eager student and tell them you want them to help you "make the truth your own." They will eat that up. Then have them prove their claims. Beware them changing the subject if you have them dead to rights on something. Hold them to follow through with a claim. I have caught them doing this and told them that "it stumbles my progress if I go off to some other topic before I get an understanding of what we are talking about now." You have a right to be stumbled when they are nonsensical, so assert it when you get the chance.
They won't admit it, but when you ask them to prove their threadbare claims, which they often can not, it jars them a bit. It creates tiny cracks of cognitive dissonance, if even for a moment. These can add up, and while you might never see the result, most of them get out eventually when this hits a certain threshold.
One final thing. Engage them in non cult conversation whenever you can, about normal everyday things. They do not have the luxury to do that among their kind, and the contrast between JW game face and authentic personality will likely register for many of them. Be someone that they can relax with. I sometimes joke about some of the sillier doctrine, that those guys on the governing body have sure put forth something complicated for us to try and make sense of, making the us vs them distinction on a different axis than they are accustomed to. Best to get to know them real well before doing that. I get the impression that they really hunger for authentic relationships, and will go a long way with your questioning their doctrine as long as you are not insulting about it.
best, Kurt (the perpetual study)