Ok...I will try not to be mean, but rather constructive. Not bad for your first vehicle. The issue I think you are running into here is that large flat surfaces paint up completely differently than smaller curved and textured surfaces. This gives your tank massive streaks and brush marks. Easiest way you can counter that is tou use way thin paint and patiently add up layers to get color depth without making the chunky streaks.
The mettalics on the tracks worked out well...smaller area = easier to detail paint.
Hope that helped out a bit...keep 'em coming!