Go slow. Pressure is anathema to self-improvement, you just implode. I've been trying for the last six months to get into a routine of teaching myself things, and I've only just got to the point where I can look back on my night without noting that I could have accomplished as much within ten minutes of motivated effort.

Don't load up on textbooks. Buy one and finish it before devoting yourself to the next one. I didn't follow this rule, and now I have stacks of books that I'm trying to read in parallel (this is going terribly).

I think it's great that you want to do this! Just know that even wanting to improve yourself is a small victory - too many of my coworkers are happy to only know as much as their jobs requires them to, or (more accurately) so they believe it requires them to. Keep me posted on how stuff goes!