@Kris: I weathered the tracks first, cos I knew I couldn't reach them once installed - they will get muddy soon - and I mean
muddy 
@Captain94: I used my new Iwata airbrush (HP-B Plus) - with the first few strokes, the paint was too thick (it splattered a bit) so I thinned it down a somewhat
after that I held the airbrush about half an inch from the surface, gradually building up a fine line - after that I backed off and made the lines a bit wider. Take care when doing this, accidentily pulling the trigger too much will result in LOADS of paint running down the model...
I have a (simple) Badger 150 too - with the Fine tip and needle, these used to paint the squiggly camouflage lines on the Bf-110 seen below (I normally build aircraft - this is my first armor

)
I like my paint the consistency of milk (low fat

) and I keep the airpressure way down - as the Iwata brush is gravity fed, I can turn it down even more compared with the Badger one...
I don't care too much for overspay with armor - after a couple of coats of dullcoat (spelling), washes, pastels, drybrushing etc. you won't notice it that much - besides, the camo was applied
in the field in real life... and I bet THEY had overspray too! so it adds to the realism
(if you don't like it, you can moisten a wide brush with a little bit of turpentine and gently wipe away the overspray - done gently, this can give great results!)
One note though - the tank is only in primary colours... it will take some beating in the days to come