What is the best rendering setting in VRay to speed up rendering while maintaining good quality?

To solve this problem we shall set the Secondary Bounces to Light Cache in the Indirect Illumination tab.
The light cache collects photons on points that are going out of the camera to the scene.
This mode is very similar to the Photon Map mode, but it is better, because it is optimized so the collected light is in the camera space, not spread all around, thus saving resources, and concentrates the calculations to the visible area.
After changing the Secondary Bounces in the Indirect Illumination to Light Cache, scroll down a bit and unroll the Light Map settings.
Set the number of samples to 500, and sample size to 0.005.
Also, turn on the Show Calc.
Phase, so you can see as the samples are gathered.
You can leave all the settings as they were.
Hit render.

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Best settings depends upon your scene 

there are no general "best render settings" for all scenes, never will be, you have to experiment according to scene lighting conditions, it'll also help you get a better understanding of what does what ..
not taking the easy way out will prove to be much better in the long run.
i hope this helps

I do share the happiness with you, that we were all enthusiastic and good to go, when we discovered Vray for3D Studio Max.
Later, you probably found out that it does not always work that good, and you need to add some lights to cover some dark places, had to jazz up the settings to make the scene look OK, scene was blotchy and so on.
There are2 solutions to this problem: Change your rendering software and find some other great plug-in for3D Studio Max that does the job better Or, learn to use Vray properly There are other cool rendering plug-ins that do a great job, but let’s not all blame others.
Also, Vray is probably the best renderer out there, powerful, flexible and really realistic.
Instead let’s check out WHY is our scene rendering slowly or (and) not correctly.

there is no best setting to adjust in vray.
its a matter of try and irroer.