For general practical guides I'd look at one or both of:
* "Practices of an Agile Developer" http://amzn.to/9B7hJg, which talks about various practices in a fairly methodology independent way. The reason I really like it is that it has some excellent pointers for checking when adoption is/isn't working.
* "The Art of Agile Development" is another nice book http://amzn.to/bksP7T in a similar vein. This is more process-prescriptive though (they're talking about a varient of Extreme Programming)
I'd also also take the time to read the seminal books on the two most important (in my opinion) agile methods:
* Agile Software Development with Scrum http://amzn.to/bOkPZ1 - the book that formalized Scrum
* Extreme Programming Explained: Embrace Change - the book that formalized XP. Read both the first http://amzn.to/cdLAtx and second http://amzn.to/bqMhEa editions if you get a chance. They're interestingly different.
I'd also add the various books on Lean by Mary & Tom Poppendieck http://amzn.to/9wsASi and also 'Kanban' by David J Anderson to the list http://amzn.to/en6PQ2 as well.
You might also find these of interest:
* The Scrum Guide - http://www.scrum.org/Scrum-Guides
* The Agile Atlas - http://agileatlas.org/
* The Agile Alliance's Guide to Agile Practices - http://guide.agilealliance.org/
lots of useful info there ;-)
Delivering software to your customer is an interaction. You need more of those, not less of those.
"Stories are "just right" when the whole team can finish four to ten per week, or about six on average." [0]
"For stories that are too big, work with your customers to split them into smaller stories." [0]
If you think it's just "Everything gets shipped every day or two and no other changes get made to how the team functions." then I have not been clear. It's a massive mindset shift, and it comes with a number of other important changes, all of which are best read from the experts themselves, rather than interpreted through me in an HN comment.
Suffice it to say, it's all been accounted for. Agile works.
[0] https://www.amazon.com/Art-Agile-Development-Pragmatic-Softw...