Maybe it's common sense to some people, but this is how I get someone banned/warned that I don't like...
First, of course I need to scam some gold (using a scammed account of course). There are many guides of how to do that here.
Next I send off all the gold from both accounts, including gear and what not, to the person I don't like. So when both original owners try to retrieve their stuff and account, all arrows point to my enemy

I have done this a few times, and have gotten good results. Enjoy