For what it's worth, this is what I've used:
Shoulder Bells:
* Several base coats of Rust-O-Leum "Aluminum" paint. Very metallic looking, yet not "flashy-looking" like "Chrome" or "Silver" paint can be.
* Mask the dents and scratches, then apply a coat of Krylon "Ivory" ("Off-White" works well too) for the primer.
* Mask the areas where you want the primer to show, then apply a solid coat of Rust-O-Leum "Farm Equipment Yellow" (designed to match "Caterpillar" brand equipment, a tad darker than the Wal-Mart "ColorPlace Caterpillar Yellow" so you don't have to use as much "Pumpkin Orange" to darken it).
* Lightly mist it with "Pumpkin Orange" from about 3 feet away to darken the yellow slightly, then lightly mist it with the Caterpillar Yellow from about 3 feet away to blend/lessen the "orangey-ness" of the Orange.
* Allow the coats to dry before the next coat is applied, of course.
* Remove masking tape and you're set.
Chest Armor:
I used Rust-O-Leum "Specialty Camouflage Paints Forest Green #1919" with a tad of Krylon "Hunter Green", though the Dark Forest Green is pretty close by itself.
Availability (or where I bought mine):
Krylon Aluminum: Wal-Mart (regular store)
Krylon Almond: KMart
Rust-O-Leum Farm Equipment Yellow: Wal-Mart (SuperCenter store)
Krylon Pumpkin Orange: KMart
Rust-O-Leum Forest Green (#1919): Home Depot
Krylon Hunter Green: KMart
Krylon dries a LOT faster than Rust-O-Leum, usually 10 minutes compared to 2 HOURS. :facepalm Unfortunately, Krylon's "Farm Equipment Yellow" is designed to match "John Deere" products, and is VERY bright, and is basically unusable. I didn't try Krylon's "Aluminum" because I couldn't find it, so I used the Rust-O-Leum version because it was available.
After the paint dried and the masking tape was removed from the metal & white "primered" areas, I burnished and scratched the armor using a wooden stick. I then mixed black acrylic paint with water (1 part paint to 10 parts water) and "blackwashed" the scratches to create carbon scoring marks. The paint is so thin that it collects in the creases and crevices. Take a paper towel and blot the surface of the armor LIGHTLY to remove any excess, but allow the paint to "pool" in the nooks and crannies. The big cut in the armor is about 1/8" deep, and the two round impact "craters" are about 1/4" deep. For these, I heated up the Sintra and pushed into it with a dowel to create the craters. The big cut was made using a Dremel sanding drum.
It may not be movie-accurate, but I got the effect that I wanted, and in person, it's pretty convincing and a lot more 3 dimensional.
Of course, there are a million ways to paint these parts, and a million brands/colors/types of paint that you can use to get similar results. These were what I used. I hope it helps someone.