Mixing Soil

Guys,
My first grow is moving along with a few probs I would like to avoid on my next grow.
First, I used MG with time released nutes, didn't work well for me,

SO

I bought some Fox Farms, some Perlite and Vermiculite to mix up my next soil.

Question: Should I mix these with the Fox Farms?
AND
If so, what ratio?
AND
Is there other beneficial ingredients I should add from the git-go?

I will be using 3 gallon pots and 400watt HPS indoors and doing Auto-Flowers.

Thanks in advance

Perlite and Vermiculite do about the same thing.
Add 25% by volume perlite to FF soils.

Thanks,
So no advantage to adding vermiculite at all?
Any other suggestions Dr ?
AJ