turn OSA on and set it to atleast 11 preferably 16
turn raytracing on and use ray variables for the metals and transparents
turn AO on and set it to atleast 10 for final renders
use sun, spot with shadow only, and a few lamps for good overall lighting
OSA is imporant, though you’ll find that climbing the ranks from 8 to 11 to 16 can make a quite petty difference.
Raytracing is indeed one of the best solutions for metals and transparents.
AO is not the end all of lighting. It has its place, and its place is not in every render. (AO abuse thread, anyone?)
The lighting that Prince has described is, again, only sometimes useful. I perfer Area lights with high samples for realism, as well as some basic low power lamps to illuminate areas.
You’re doing well so far! Keep it up!