Definitely purchase Bill Keogh's book The Florida Keys Paddling Guide. It is
well worth the money. Available on Amazon.

Bill's guide service is also a good bet if you would like a guide.

Look for directions to The Old Wooden Bridge Guest Cottages and Marina on Big Pine Key. This is where he operates out of.

http://www.oldwoodenbridge.com/

Here's the link to his site ...

http://www.keyskayaktours.com/

The book has every conceivable "put in" listed by mile marker from Southern most point to Card Sound.
Along with some historical and ecological info near each "put in".

I have a ton more info on launches/wading/eats/etc. but too much to post.

Send me a PM or e-mail me if you'd like some more info.