I technically started with access to a TRS-80 Level I, but it was the Color Computer that really started me down the path I'm currently on. It helped that it booted into a BASIC interpreter. I eventually got an assembler cartridge for it, and used it mainly to learn 6809 assembly language after quite a few BASIC programs. Somewhere I found a memory map for the machine, and I was off trying to recreate my favorite games. I think I still have the 6809 book I bought back in the day. I remember a lot of trial and error, and a lot of time spent fiddling with the cassette player to load and save programs.

The mindset at the time was "I have this, what can I do with it?" Now it's more like "I need to do this, which of several ways is easiest/quickest/less hassle/etc."