The single most important is :
Have a clean Windows 7 system.
Defrag it.
Run something like, and it just came out;
Advanced system care free, version 5 from iobit.
Run deepclean , a one click solution.

Or Glary Utilities, or Winutilities, certainly CCleaner.

Please forget all about AO and IBL light if you are rendering with IDL ; ON.
It works, but is not worth the internal calculations time rendering battle.

Lights; I can be very short on this subject. There is only ONE sun.
For outside renders : Always render with ONE infinite light in BB's sphere.
That is more , and I repeat more then light, as mostly you will have to turn the light down to 50-60% in intensity.

For inside renders, use ambient where needed.
On the TV screen, the PC sreen, the TV screen, the lightbulb, the candle.

Try:
**Cast shadows ON
Raytracing ON
Raytrace bounces 2-3 : start with 2
Indirect Light ON
Irradiance caching 0 – 30 : start with 0 (all the way left)
Indirect Light Quality 7
Pixel samples 3-5 : 3 for speed (5-7 for quality)
Min shading rate 0.5 ( 0.2 for optimum detail and 1.0 for draft)
** Bucket size 32
Smooth Plygons : As required
Use displacement maps => If you use a displacement map somewhere
Post filter size 2-3
Post filter type sinc
Gamma 2.2

Build from here.
Happy posering

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
"Do not drive faster then your angel can fly"!