Use technical jargon once in a while to keep the ignorant on their toes (and to make quacks more sure to not be opposed).
Allow comments. People want to be heard, even if they have nothing to say.
Allow spam comments to seep in after a while. That way people can feel useful for pointing it out to you.
If you don’t want comments, but don’t want to disable them (which would ensure detractors starting their own blog and possibly drawing traffic away from yours), make sure your speling’n’grammar are impeccable, then sprinkle liberally with forms like “coördinate” and “raison d’être”. Most people realize such authors are not susceptible to reason, and the rest of the commenters should be easy to deal with.
Include at least one link to something great but irrelevant, such as Stack Overflow or OpenStreetMap. A positive first impression is the best way to get the readers to fight for you, no matter how wrong you are.
Talk about the zeitgeist, but don’t ever mention the word (unless you’re going for double meta bonus). That shows you’re an Enthusiast in the Know.
Ask people nicely to be nice in the comments. They won’t be, but you’ll get more replies to vitriolic garbage from people who feel they are defending the peace-loving blogger.
Be as damning as you can about as many people as you can possibly include, but make sure it at least pretends to be DH3 or higher. If you’re writing for a particularly stupid audience you can go for DH2 (“style over content” people) or even DH1 (conspiracy theorists).
Mention which music you listened to while writing. Your fans will look it up, self-appointed aficionados will criticize it, and people with too much time will point out how irrelevant it is.
Retract something you wrote. You will be seen as either a flip-flopper to be flamed into oblivion or as a mature person willing to challenge their own opinions. Everybody wins.
If someone posts a crushing counter-argument, crush theirs by acknowledging the argument and concluding with “but the point still stands.”
Discuss the possibility of a rumor in post A, then take it as fact in post B by referencing post A as source. Instant credibility.
If you want to back up your statements with external references, use the most vague URL you can get away with – Ideally to the home page of the organization or author. If forced to use a direct link, make sure not to include #anchors and to paraphrase instead of quoting. That way, nobody except the really diligent will realize that your interpretation was “liberal”.
Write lists on the form “The <number> best <plural noun> [of <period>]” or “<number> ways to <verb> [<plural noun>]”. If your list is less than ten items, pad it until it’s at least 15. In fact, pad it anyway (but don’t make it obvious). And make sure at least one of your points is as long as the rest of the list put together, to break up the monotony. Ideally it should combine at least two points. If anyone accuses you of misusing lists (since you’re effectively compressing multiple paragraphs into an artificially cramped place), you get to be smug because of not stooping to the level of the “style over content” people. Just don’t combine with point 10. Lists should be a positive place!