I don’t torrent much, and when I do, it’s usually legit. When it’s not, I’ve got Transmission to sort of cover my rear. Nothing’s perfect, after all. Especially when it’s peer-to-peer, you just have to trust a bunch of people.
Anyway, Transmission is great because it has a peer block feature. You just point it to a list that fits its ultra-picky requirements and you hide yourself from tons of people who might be out to prosecute you should you be picking up something they don’t approve of. You know, these guys:
Companies or organizations who are clearly involved with trying to stop filesharing (e.g. Baytsp, MediaDefender, Mediasentry a.o.).
Companies which anti-p2p activity has been seen from.
Companies that produce or have a strong financial interest in copyrighted material (e.g. music, movie, software industries a.o.).
Government ranges or companies that have a strong financial interest in doing work for governments. Legal industry ranges.
IPs or ranges of ISPs from which anti-p2p activity has been observed. Basically this list will block all kinds of internet connections that most people would rather not have during their internet travels.
Get yourself the Level 1 blocklist. Follow these steps for success:
Download the blocklist in your browser.
Then get the download link, like so. It’s a one time link, that’s why you have to do this.

Open Preferences in Transmission and go to the Peers section.
Check the Blocklist box and paste in the link. Make sure Automatically update weekly is unchecked, because the link won’t be valid in a week and your peer blocking would disappear.
Press update, watch 200k+ peers get blocked. Bad peers.
Enjoy being a little safer. Repeat this from time to time to update your blocklist. Too bad BISS doesn’t have a static link to the list.