How safe is it to use torrents? Not for pirated junk, mind you, but for everyday stuff such as OpenSUSE downloads? Any special precautions I should take?
Should be fine. If you are on a quota-limited ISP plan, and uploads are counted, keep an eye on the upstream volume. You can set a share ratio in torrent clients.
You might want to check this
A Quick Bittorrent Guide (with screenshots) - openSUSE Forums
That’s what Checksums (md5sum/sha1sum) are for.
So download those from a trusted source (official Mirrors) and check/compare them after downloading.
If your worry is that recieving data from someone you don’t know is an opportunity for them to slip something nasty onto your machine, you have no reason for concern as long as you obtained the .torrent file from a verifiable source that you can trust. The others in the swarm must send data that matches the hash table included in the .torrent file or your torrent client will reject it and re-download that piece of the torrent.
The only way you can get malware from a torrent is if the ORIGINAL data used to create the .torrent file contained it.