ummm it really is pretty easy. it just take not downloading crap. Those virus, malware writers really do not use scenarios that are not easy to tell they are likely packing a malware on them.
Easy? Well... I got suckered once, almost 10 years ago when I was on AOL, and I've never had another incident since.
I won't argue with you, but everyone is different, and these rules you've made for yourself are born out of your own experience and knowledge, as are my personal rules for me. Not everyone has that experience.
How'd I get suckered? Pride. I thought I knew all the forms a virus might come in at the time. When I saw the file was a ".txt" file and supposedly had a list of jokes, I downloaded it. I opened the small .txt file manually in notepad (didn't double click), and notepad informed me it was too big, and prompted me to open it in Wordpad (I'd never seen that before). In word pad, a single image sat there with a small icon of a butt, and it said "click for a laugh". At that point, I'd momentarily forgotten my quarantine procedures and the embedded script got launched. ZAP. Next thing I know I was being key logged. Soon the person was using my e-mail account to send messages to all my contacts, pretending to be me, with a "special download" related to my profession. What a nightmare.
I've seen some truly twisted tricks out there in recent years, and I wouldn't dream of blaming a non-computer person for accidentally becoming a victim. These days, I hardly pay attention to spam, but I get questions from friends asking about the latest OEM software vendor or virus hoax being forwarded. Most tricks are lame, but others, unless your cynical like me or yourself, are quite persuasive.
~ CB