This is, 100%, the most immediate thing you can start doing to start seeing progress. Conditioning allows you to train harder AND recover better from training, which doubly perpetuates awesomeness.
For books to read, I am a big fan of
Purposeful Primitive by Marty Gallagher
The Complete Keys to Progress by John McCallum
Powerlifting Basics Texas Style by Paul Kelso
5/3/1 Forever by Jim Wendler
Brawn by Stuart McRobert
Super Squats by Randall Strossen
Mass Made Simple by Dan John
The Easy Strength Omnibook by Dan John
There are many other great ones out there as well, but those are a solid start
For authors to read from T-nation, read as many of these articles as you can
Here are some other choice ones