Here’s my basics:
Anti aliasing buggers up everything. It totally undermines every other sampler in vray as every time vray goes to render a bucket, it first calculates the material and lighting sampling. This gets passed back to the anti aliasing to decide if it’s good enough and if it’s not your anti aliasing goes up to the next quality level and so on. It means that you’ve got two options on how to solve your render issues in vray, one is with really high anti aliasing to solve everything, or make sure your sampling is good before it gets passed back to the anti aliaser so it “approves” it as such.
What I do now with passes is the following:
Sample rate to check AA
Raw lighting to check grain of my area lights
Reflection to check materials
Raw reflection to again check materials (this can be misleading - raw reflections will boost reflection strength to make it almost chrome like which may be stronger than your actual material ref strength)
MTLGlossiness - Handy to see is it an overall noise problem - since this gives you a guide of what glossiness value all your materials are, you can see are ALL of your blurry materials noisy or just some.
Raw global illumination to check GI undersampling errors
Your sample rate will start to evolve and become less red as you start clearing up your material and light sampling issues, so you can gradually bring down your Max aa until you get a nice balance of clean and speed.