I am pathetic at this game. I doubt I will do better than bronze in the coffees breaks.
All I know is I got silver first time out on S-1. I will redo it for gold and let you know what I find out.
I assume you are using manual. If so test to see where acceleration stops ie at the redline or after it. For lowish powered cars I generally change up at the point acceleration stops (normally just past the redline) as this helps in the next gear. Obviously this can depend on whether there is a corner coming up but if not then this is the technique I use.