Literally only months passed between the time I watched the entire OT and the release of TPM, so I didn’t have a whole lot of time to build a cohesive headcanon of the PT timeline before it was disrupted. Regardless, I had come up with some hard concepts:

Anakin was older than nine years old when Ben discovered him
Anakin had black hair
Anakin’s wife (who wasn’t a queen or a senator) had red hair
Luke & Leia were born before Anakin turned to the dark side and raised by their biological parents on Tatooine for the first years of their life
The clones in the eponymous Clone Wars were proto-stormtroopers who fought against the Jedi and the Republic
The Mandalorians were a secondary enemy force who participated in the Clone Wars and were wiped out by the Jedi
The Empire already existed with Palpatine as its emperor before Anakin’s turn to the dark side
Anakin deliberately killed his own wife
The Great Jedi Purge spanned a number of years before Anakin fought Ben, fell into a volcano, and became Darth Vader
Hand-held blaster technology wasn’t invented until the rise of the Empire