Books are good, but some things are unlikely to be learned that way. For
instance, you can probably learn the paddle float self-rescue from a book but I
doubt one could learn to roll from most of the descriptions in books. In my
case I think that the expectations I aquired from books really made it more
difficult for me to learn to roll.
Even if you are a "loner" I would join a local club. You may rarely
paddle with your club but they may put you on to some sources of instruction
that are cheap to free. Our local club has occaisionaly talked certified
instructors into giving classes to our club for free. Also, there are some
experienced kayakers who seem to enjoy teaching more than paddling.
Kayaking is more than just physical skills. The ability to plan and know
what you will encounter is just as importat. How did you guys and gals get
started kayaking? Work your way through
formal instruction? Friends? Get a book, a kayak and start self
teaching? Just wing it with a kayak? Any and all types of kayaking
would be of interest.

It seems like group classes and trips are certainly the popular thing.
I think the social aspect of the group activity are as much a draw for
some people as anything.

I'm much more of a loner and find that although I have the time, it's
a few hours here and there, and I never know when it will be. I'm
leaning toward the book and kayak method. I've spent my whole life on
the water (49) and have experienced most fazes of boating, including
extensive wind surfing and dinghy and catamaran sailing. But, I
haven't done the kayak thing yet and it seems about the right time.

After I get comfortable with a kayak in protected waters my current
opinion is to at least get with someone and learn to roll.