Learn about getting input - buttons, switches, potentiometers, etc. Then go for motor control: Servos, steppers, DC motors, relays, solenoids, h-bridges, PWM,

Learn about getting input - buttons, switches, potentiometers, etc. Then go for motor control: Servos, steppers, DC motors, relays, solenoids, h-bridges, PWM, etc. Add in some other sensors - perhaps ultrasonic distance sensing, Sharp IR sensors... ...then move into hacking on a Neato Lidar sensor... At this point - build a robot?