Accolades are earned by winning championships, invitational events, and some manufacturer events.
Accolades come in gold, silver, and bronze varieties, but that is completely irrelevant as far as this achievement goes. Any combination adding up to 50 total will unlock this.
Completing 'Zero to Hero' will give you between eight and 12 accolades depending on which route you take.
You will probably have unlocked enough invitational events to complete 'Mr Popular' now, potentially giving you another ten accolades.
Focusing on 'Cream Of The Crop' will earn you another six.
That adds up to between 24 and 28 by this point.
The most efficient way to earn accoldes now is to complete invitational events. Unfortunately you will need to win championships to unlock them.
Personally, I went for the other career based achievements and completed invitational events as soon as they unlocked. Doing this got me the achievement just before I finished off the career stuff.
You can check how many accolades you have earned by going to the far right 'progress' tab under career.