I handpainted my yellow bars on with acrylic. Then used an x-acto knife to scrape away at certain areas. I thought the effect was nice. You might also mist it with a spray or drybrush some grey over it.
You can buy sticker paper at most office supply stores and just print directly on them. Most chest and shoulder designs are decals or stickers, but I would definately recommend painting or stenciling the ocre stripes.
the sticker paper stuff can be a real pain(if you get a bubble or it doesn't go on straight it makes you want to cry because you need to replace it..then the sticker rips..etc etc) so i would advice to just amke a stencil, tape it down nice a good, make sure its nice and centered and lightly spray over it giving it a few minutes to dry so ya don't get drips
Nice tip, Slave. For those of you going for complete accuracy though, the real shoulder and chest emblems were decals. Ego makes the most accurate skull decals I've seen, both ESB and RotJ (yes, they are slightly different). That thread is around here somewhere.
i found that if you want great yellow / red marks on your helmet that it is best to use a sponge . just cut the shape and size , dabb it in the chosen paint , then dabb it on paper to remove excess paint . then apply it to the helmet . this gives it that worn off look.