The most important thing is to choose a style that you're comfortable using. Mine involves a lot of profanity and run-on sentences. The second most important thing is to be concise, clear, and definitive. Localroger will use any lapse in clarity to weasel his way into a different argument (one that he could possibly win), so it's important to get it right the first time so you don't have to spend three frustrated comments trying to lead him by the nose to the point.
To this end, use definitive wording, and repetition. And do your best to identify typos and grammatical errors beforehand or else you'll get worthlessly smarmy little quips about it.
2. Always follow-up.
Localroger loves to skip points he can't find a suitable retort for. Don't let these purposeful omissions become a missed opportunity to slap that fathead right in the face with them.
3. Read between the lines.
Localroger will sometimes carefully choose his language, trying to purposefully avoid a weakness to his argument he knows about. Read for him using indefinite language, as when he knows absolutely nothing about a subject he generally speaks as a definitive authority. Let's look at that again: when he doesn't know what he's talking about, he's absolute; when he does so he can see the flaws in what he's saying, he wavers. What a beautiful gem of a guy.
4. Read behind the lines.
This doesn't really apply to everyone, but if you're a complete shithead like me and you've turned the "Personal Attack" knob to 11, here's a tip. Localroger always talks about how what people do on the internet is some reflection of deeper psychological issues. I think that's because that's what HE's doing and he likes to apply his methods and motivations to everyone else. Read behind the text to figure out what motivation writing that stuff is satisfying (hint, it's usually to boost his ego). Then take that away.
5. Remember EVERYTHING.
Obviously this isn't something for everyone, but I'm cursed with a really good memory and it helps. If you're attacking localroger's argument or localroger himself it's generally a great tactic to use his own words against him. His behavior has shown he's obviously ashamed enough of getting it wrong that he'll erect huuuge fences of dissonance to compensate. But beyond that it's good to know localroger's habit. Knowing how he's going to respond before he responds lets you control the way the argument is going. Localroger's methods are nothing if not predictable. He's used the same few arguments against me for months and generally it's easy to push him into one of those.
6. Know the man.
Once again, if you're a douche like me and your goal is just to attack the person, it's important to know where localroger comes from. Knowing that he's the epitome of underachiever gives me access to all sorts of avenues of attack: make him look insignificant, make him look like a failure, make him look like a fool. When you don't know something, just make an educated guess. Self-righteous roger will be quick to come in and correct you, thereby revealing more about himself for you to use. In the past two days I've learned all sort of information about his job by just making it up on the spot and having him correct it. And because of that, nearly all of K5 has learned that Roger's bosses are manipulating him through his ego into being overworked and underpaid, and they have him grateful for it. You add to this his epic story about having to go to mexico because his dental insurance sucks hideous balls and you have even more.
When you're arguing on the internet with a self-absorbed prick the war of information ALWAYS leans in your favor. It is your single greatest asset.
7. Check the facts.
Like I said before, LR loves to speak definitively about things he knows nothing about. The greatest thing to shove in his face after his own words are the words of a definitive source. When you do this, he'll go into a spiral of excuses and deflections. This is a huge weakness and the prime time to press your point.
8. Know when to quit.
I know this is rich coming from me, since I never know when to quit, but you should take a lesson from that. A 2000 pixel wide thread works in noone's favor.
9. Use hubris to your advantage.
It's ok to show a little weakness up front to draw him out. When you combine a weak/empty argument with pointlessly inflammatory language, it's more likely your opponent will become filled with righteousness and overreach. With localroger this is practically guaranteed, as it appeals to his desire to prove that he's better than everyone else.
10. Always maintain your credibility.
This is another one of those that's rich coming from me. But another that you should learn from my mistake. Constantly being relentless, and vicious will lose you your credibility. You have to choose your battles and change up your MO or people will in general just start ignoring you. However, localroger will never start ignoring you, because he's pathologically driven to try to be smarter than you. It's very easy to continue digging because that insufferable ham will always try to have the last word.
I hope this guide has helped you become a better asshole on the internet. If it hasn't, I hope it has helped you realize what a sad, sad man I am.