I was having problems getting the yellow outlines on a Soviet star tissue decal to stand out. Tried a variety of Prismacolor pencils but no luck. I had an oil-based Sharpie marker but it wasn't very good at fine detail.

I saw these on Amazon and gave them a try. Not very expensive and produced a better opaque sheen. One issue was that when used on tissue that was still attached to my backing paper, the ink soaked through and stuck the tissue to the paper. Next time, I'll remove the tissue decal before inking it.

https://www.amazon.com/dp/B07MZG2VF8?psc=1&ref=ppx_yo2_dt_b_product_details