Here's how I learned (most) everything I know:
When I was 13, I made a deal with my neighbor where he gave me a Pentium 200Mhz PC and I did yard work for a year. From there, I was always on the thing. Breaking stuff so I knew what broke it, and then figuring out how to fix it. I must have gone through the Windows 95/98/98SE/XP install process hundreds of times over the years because I broke it beyond repair. That however gave me a good understanding of Windows.
People say that they don't really learn much from books. Someone like myself hates reading books because they are so dry and slow (from a learning prospective). However, I have found that some of the most detailed knowledge is found in books. Practicing SQL queries won't explain SET operations and predicate logic... you'll only find that in a book or a good mentor.
Probably where I've learned most new stuff. Have a question? Google it. Even if you don't find the right answer first, you gain a lot of perspective by reading through forums (like this and others) on how people attempted to fix issues and how they were finally resolved.
No one source of knowledge is going to make you the sharpest tool in the shed. Can you build a home with only a hammer? Well, I'm sure you could, but it wouldn't look near as nice as if you employed every tool at your disposal, right?
Pick up what you can, where you can, whenever you can. Learning should never stop, don't become stagnant because technology will leave you right where you stopped.
As joedaman pointed out, everyone has their own style. Perhaps take an adult learning test. Something similar to this
may help you figure out what you're more geared toward (tactile, visual, audio, etc). You can use that to find learning avenues that match your learning style.
Just keep reading, doing and practicing. If you can't figure something out, do NOT hesitate to ask someone. Remember two quotes
"The only stupid question is the question not asked"
"He who asks a question is a fool for five minutes, he who never asks is a fool forever"
Use any and all resources available.