I think the first thing you do with a website that once ruled and has been left alone for over a decade is give up on your original core business and invent two new wearables and release them to the market, announcing them as the next revolution in wearable tech ;-)
Seriously...
1. Prioritize and Set Goals.
Every web page should have a stated goal and an action that you want the reader to take (it might have more than one that are possible, but it should have a purpose from a user point of view. Ten years ago, it might be enough to have tons of crap fluff that Google gobbled, but users didn't).
You should be honest about the action you intend the user to take. Maybe the action you want is simply "read to the end and then go off an watch TV." That's your choice, but if that's not what you want people to do, the web page shouldn't be pushing them in that direction. So he should think about what types of actions he wants people to take, set those as trackable goals in his analytics and track them. Figure out which pages are best at achieving those goals and strengthen those pages and build more content to support those pages or goals. Traffic for traffic's sake is not generally a worthwhile goal. Nor is link acquisition or search engine rankings.
2. Start capturing emails
So personally this is a big failing. I've set this up for clients better than I do this myself... but there are some good email capture tools that are so easy to implement, you might as well start now. Super simple and easy (because as noted I'm incredibly lazy about this) is the AppSumo suite of tools. What's he going to do with all those emails?
a. He is going to send out content that his analytics show is what his users most desire
b. He is going to on rare occasions make an "ask". It might be a survey to find out what the major pain points for his users are. If it turns out the major pain point is building an email list, he creates content, a free e-book, and app, an I have no idea to help people do that thing - source antique car parts, build email lists. Whatever his thing is.
c. Once he has data from #1, he creates special email-only content that is optimized to accomplish what his best content accomplishes.
[edited by: ergophobe at 6:32 am (utc) on Jun 8, 2015]