Go Beyond the Arduino
The Arduino is a great prototyping platform, and can get you building projects probably faster than any other platform out there. I cut my teeth on an Arduino UNO, and was like a kid on a sugar-rush when I got my first robot buzzing around my workshop. I built and built, and learned, and read, and experimented, and played. Then came the day that I wanted to build project that needed to be a little more permanent and with less jumper wires that could work themselves loose. I gritted my teeth, held my breath, and plunged into working with the microcontroller in its raw state. No more Arduino UNO to hold my hand, just a bare-metal ATmega328P sitting on a breadboard staring back at me.