One thing I've heard and seen over and over that the best thing to do to keep safe is to not open anything if you don't know who its from, if it's a blank email, the subject doesn't make sense, or has an attachement that isn't mentioned by the person who sent it; if in doubt delete and or ask the person who sent it!
Another thing is to use, and keep up-to-date, a good set of basic protection software; a good firewall, antivirus and anit spyware, are all pretty essential these day's; I also now use a good spam filter to filter out spam before it lands in my computer.
And, finally, if sending a group email, it's now pretty much a good practice to use Bcc or a group mail sending program or company - it helps keep the spam down.
