Hi,
to be honest in my opinion arduino is not a good idea. It actually separates you from real hardware. The best way in my opinion is to buy a development board (5-40quid), start a bare metal programming. When you become familiar with timers, interrupts etc etc - you can of course join the arduino community. Internet is the best source of knowledge.
I came back to electronics after almost 30 years, and actually now i have finished my first project (on-board glow plug driver).