It is a common path, and perhaps not the best path. Personally I feel there are two better areas to grow into. One is becoming a producer, which gives you more power - you can fire the director. Secondly, if you are looking for a skill set that is nearer to a writer I could say it would be to become an editor.
If you were there on the day of the talk then here is the Prezi we used which you may find a useful refresher.
If you weren't, then have a zoom around the Prezi by all means. But the summary is this...
One: You already have a "director's vision". You have it as you write. Don't be scared of this term or think it means something special that you don't have.
Two: Watch out for the "writers disease" - that is directing too closely to the script, pointing the camera at the dialogue all the time. Filming the speech isn't the best way. Hear the speech, see something else.
Three: Know the stages of production - now you have to see the film all the way through.
Four: Get ready for collaboration. You don't need to know everything technically, but you do need to know how to listen to people who know their stuff.
Five: Just do it. You can't learn this second hand. Like writing, you have to give it a go and take it from there.