The first general point is to treat it like normal SEO. Just track the keywords you’re targeting, track the landing pages you want to go go — do everything like you’re doing it directly for a client. It’s just that, your client doesn’t know. And if he did, he would hate what you write about him.
The second general point is, be analytic about it. Don’t just find something bad (but true!) to say. Treat it like a number you want to optimize for. Obsess over it. Follow it every day.
The third point is, be creative about it. Where can you post (things that are bad, but always true)? Where would he never expect it? Post, post, and post away!
Fourth: Be obsessive about it. Did I say that? I can’t emphasize that enough.
That’s enough to get started. Of course, there are lots of advanced things you can do to help the negative online marketing. But those are for another day.
The hardest part? Getting started. Dealing with your own psychology, of being negative.
Honestly, it’s hard. We want to be positive, fun, happy, smiley. But to do negative marketing (not to mention, negative SEO) very well, you need to get dark. Very dark. Do you want to go there? Are you sure?
If you do, then enjoy it. Revel it in. We laugh at the things we do, we really love it.
But don’t stop. To crush your enemy, you need to crush them completely. Completely.