I'll consider myself a nonparticipant in Politics because though I post there once in a while it's nothing substantial and I usually regret it.
To answer the question in short, nothing. Politics is the worst possible thing to talk about, unless you consider abortion to be a separate topic in which case it's the second worst. Any political discussion inevitably boils down to ideology. There is no point discussing ideology. It's a matter of belief not reason. And nothing irritates me more than ideology presented as fact. Conservatives are probably irritated by my ideology too, but at least I'm not arrogant enough to assume it's the One True Way all the time. The saddest thing about host's posts is that they're totally lost on the people who could use them most.
of course, this is all imho 
Let me add, I do enjoy
reading Politics. Its very informative, and sometimes entertaining. But the
discussion/
debate part, not really for me. I don't seriously believe I'm going to influence anyone's opinion, nor am I even sure it's good if I do or that if I did it would make any difference. That's what separates me from the politicians. Would that I could offer constructive input but I usually feel like I'm not contributing much.