Now, I don't know shilling, but I do know samefagging and trolling. And it doesn't require much more than a few sleeper accounts and mastering a few different writing styles. You also can't just jump in and start posting. You need to be as flamboyant as possible, spewing garbage into every topic you can. Post in everything. Then, once you have a few hundred post in each account and some good karma in at least one account, you can start modding comments up.
The actual important part isn't even that though. You should start fights.... with yourself of course, and this can be done anonymously. use one name to post an simpleminded, ignorant argument, and use the master name to knock that strawman down in a reasonable manner. Not only does it make it look like you weren't the one who brought the topic up, but it makes you look more insightful when juxtaposed to some inane, asinine garbage. You should always do this reasonably in the master name, but act like a retard ideologue on the retard account. Ideally, there should be several retard accounts for a single master account, but it can also be good to have a few master accounts that both agree on the general point that you are pushing, but disagree on the trivial details that are only seen from an ivory tower. This is far better at creating an illusion of consensus than arguing with others.
And the most important part is this: never, ever, attempt to argue with others. You should never let your control of the discussion slip. If others start to respond, use the retard accounts to drown them out, then continue arguing with yourself.