I use
uTorrent as my download client and
isoHunt is where I find most of my torrent.
I've been downloading torrents for about three years and haven't had a single issue. I also have good up-to-date anti-virus software and I'm smart about what I download. I don't download any rar, iso, or zip files, only mp3 and avi. I've downloaded a few pieced of software (exe files) but I don't like doing that because those can definitely be dangerous. I usually just download programs like that for the keygen and try to download a trial version from the actual site, then use the keygen to unlock it.
I mostly use it to test out music or a movie I've been thinking out. If i really like a CD or movie I download, I almost always go out and but, otherwise, it gets deleted.
NOTE: If you use isoHunt and you're looking for movies, search for aXXo. He has uploaded a ton of movies and they're always safe and high quality.