Like I wrote before, Asimov didn’t know that the Foundation Series would become that big and that he was going to connect the series to Robot and Empire. So, in the ‘Author’s Note’ at the beginning of Prelude to Foundation, he offered his own reading order a chronological order, to be precise.
I, Robot
The Caves of Steel
The Naked Sun
The Robots of Dawn
Robots and Empire
The Stars, Like Dust
The Currents of Space
Pebble in the Sky
Prelude to Foundation
Forward the Foundation
Foundation
Foundation and Empire
Second Foundation
Foundation’s Edge
Foundation and Earth