in addition to reducing the raytrace bounces its very important to actually go into your material editor and tweak the settings of all your reflect/refract materials.

if you have large reflective objects and theyre set to something like 1.0 quality with softness, it will take exponentially longer to render than if they were set to 0.1 quality. ive been able to set reflection quality as low as 0.01 and still pull off decent effects.

i would not lower pixel samples too low. yes its a rendertime hit, but nothing looks worse than horrible aliasing in a scene.  what you set it to depends on your scene and background, but ideally you should bump it up until the jaggies go away.

as suggested, .2 shading rate is good.  i used to render everything at 0.00 but the difference is very minor but the rendertime hit is quite large. i crank the hell out of it to 4.0-8.0 for preview renders since it makes them render lightning fast and you dont need shader detail for quick lighting tests.