The NSA has published a nifty Best Practices for Keeping Your Home Network Safe fact sheet. This is a pretty good document which mixes easy-to-understand concepts with some more challenging ones. I really feel that people can get overwhelmed with the technical stuff, but usually do react favorably when given managable challenges.
I’d like to have seen more emphasis made on unique, complex passwords and the importance of passwords, but these are still excellent bullet points to cover with people. Entire books can’t cover the breadth of tips for good security these days, even for the layman….