Zanex,
Many posters have made good points. Decide what you want, then pick an appropriate strategy. Here is what worked for me.
My brother-in-law was an inactive JW for 18 years. Then, he got active again and is totally overboard zealous. Every topic is somehow turned into a "witness" when he is part of the conversation. Typically, such "witnessing" goes on for about 3-4 hours or until someone rudely tells him to shut up.
When I get tired of his ravings, I just politely disagree and have very good counterarguments. For example, if he takes about the last days, I tell him about how our standard of living is higher, how our lifespans are longer, etc. and back these up with hard facts. Soon he is floundering as the WTS never talks about how we now have unemployment insurance so we don't starve between jobs, how infants rarely die now, how the lifespan is now 80 years instead of 40, etc.
I explain how Bible prophecy told people in the 14th century that they were definitely in the last days. I explain that we don't have pestilence anymore. Entire villages used to be wiped out by pestilence, but that does not happen anymore.
If I am in a especially nasty mood, I will point out how the WTS is the worst guide to follow about the end times. I will quote Russell and tell my BIL how Russell knew the end was coming then, by 1914. I will quote Rutherford about how the 1925 date was God's date not man's.
Once, I start doing this, my BIL suddenly has to leave. We have never discussed it more than five minutes once I start at him. At that point, I am the one wanting the discussion to continue!
I have used this method on several JWs, with similar results.
Most JWs only know what the WT tells them. When exposed to alternative arguments, they tend to flounder.
Richard