Global Scale Modeller

Can someone best explain at what stage of the painting process do we apply filters to our models?
I have a set of sin industry (mig productions) for german vehicles which I really want to dig into.

So say I have just completed painting my afv using acrylics, do I need to varnish it before applying the enamel filters?

-do I weather up with streaks and rust and pigments, then filter

-do I apply filter straight onto the acrylic surface then apply weathering products.

Can I use say a clear coat afterwards to varnish and seal everything together?

Thanks guys hope it wasn't confusing

The quickest answer is to start with Coen's guide:

http://intscalemodeller.com/viewtopic.php?f=66&t=8369

Oh thanks so much. I totally forgot about that