*my personal opinion (as someone who hasn't built a full suit yet, but has built a number of props and helmets)*
even if you are going for a clean shiny set, I think weathering is a must.
I've had a lot of luck with water-based acrylic paints, brushed on heavy, then dried a little, then cleaned up with a damp cloth.
to my eye it gives the look of a suit that got dirty and has been cleaned by the user (cause that's literally what just happened. :-P ).
but I'm also a little biased, I tend to weather almost everything I own...