Admittedly I haven't done as much studying and learning away from the tables this year as I normally do. I just haven't had time with all the hands I'm putting in on a daily basis. But normally I do spend a lot of time learning. Here's a list, in no particular order, of what I've done over the years to build my knowledge:
I used to read every single piece of poker literature released ranging from Theory of Poker to Bad Beats and Lucky Draws (I don't ever recommend reading this other than to laugh). I eventually stopped as the market became over-saturated with poker material but I still filled an entire floor to ceiling bookshelf. Nowadays, I occasionally order books on my Kindle. Next year I plan on ordering a few no-limit books.
I also used to surf to every poker site I could find and read through all of their strategy articles. One of the sites I've always enjoyed is Cardplayer, I like Roy Cooke and Matt Matros' articles in particular. Also, the 2+2 magazine has some really good articles. Some are complicated and go way over my head but others are easier to follow and I've learned a lot from them.
I've done a lot of this over the past couple years. Before my computer crashed earlier this year, I had a database of a couple million hands so I was able to analyze even semi-obscure situations and still have a reasonable sample size to draw meaningful conclusions from. Nowadays, there is so much data out there available for purchase that I think meaningful analysis could be done using other player's data especially winning player's data. For anyone unfamiliar with this, Hold-Em Manager is one of the best programs out there for analyzing data.
Subscribe to a Poker Learning Site
There are a number of these sites out there, the two I use most are StoxPoker and Cardrunners. I have links to both at the top of my blog page along with SureFire Poker. SureFire is exclusively no-limit and Omaha and has arguably the best NL player in the world (OMGClayAiken) making videos. I really can't say enough about these sites, they have some of the most successful online players making videos of themselves playing while explaining each decision they make in detail. For me this has been a huge part of my development and learning. I still watch 1-2 videos a week.
Discuss Poker with Friends
This is something I haven't done much of this year but used to do all the time. I was lucky enough to meet a friend, Rory about 4 years ago and we'd discuss all sorts of poker topics via email. He helped me immensely with my game not only with his ideas but by asking me a lot of questions and really forcing me to think about the game. If you're able to find someone like this, take full advantage of it, it's a great way for both of you to learn.
Use Software to Analyze Hands
I guess this could have gone under the analyze data section. Two programs in particular I've found really useful are PokerStove and StoxPoker Combo. PokerStove is free and I believe you need to be a member of StoxPoker for the Combo software although there is comparable free software out there (not sure of the names). Both of these programs help to simplify the math when breaking down hands to determine your best course of action in the hand. Something I've found really helpful and that I've been doing this year is: Any time I'm confused or unsure of what to do in a hand, I will copy and paste that hand into notepad and then go back after my session and use PokerStove or StoxPoker Combo to analyze the hand and try to come up with the correct decision.
Hire a Mentor or Coach
I've never had a coach but I've had a few friends that have been mentors. If you're really serious about getting better and taking your game to a high level, a coach is a great idea. A lot of the poker learning sites have coaches and although it's a bit pricey if you're starting out, the upside of what you can make playing poker far outweighs the coaching costs.