I get a lot of questions about how to develop the skill set of a master knitter. Step one is just spend a lot of time knitting. However, the next part is where it gets hard. You can't keep knitting the same things in the same ways if you want to increase your skills.
There are some programs around if you want something formal TKGA has one here: http://www.tkga.com/?AboutTKGAMasters They are here on Ravelry.
There is a Canadian program here but from what I can see on the website they may have stalled out at level 2 of 5 in terms of development. I was unable to locate a Ravelry presence for them.
I think for many knitters the relaxation they get from knitting is the goal and if that's you, it's a great place to be. If you are one of the knitters looking for more challenge you can find it by simply choosing patterns with skills you don't yet have.
You can also take some advice from Joshua Foer who says "experts – those who excel beyond all others in their fields – do it differently." Foer identified four principles that he saw experts using to keep learning:
1. Experts tend to operate outside their comfort zone and study themselves failing.
2. Experts will try to walk in the shoes of someone who's more competent than them.
3. Experts crave and thrive on immediate and constant feedback.
4. Experts treat what they do like a science. They collect data, they analyze data, they create theories, and they test them.