A few tips:
Thin your paints a bit more, especially the gold on the Aquila. It's obscuring some of the details on the chest and gun.
Look into colour theory. You want to use a combination of light and dark (which you're doing already!), complementary colours (what about some purple or blue details somewhere? Gun lens? Purity seal wax? Eyes?), and a combination of cool and warmth. In general the model is quite neutral, but that could be chainged easily by...
Throw a dark shade over the yellow, then drybrush lightly with a bright yellow. That way you'll get some really nice warmth and contrast on the sharp edges of the model.
Consider edge highlighting the edges of the shoulderpads.
Best option from a spray is Tamiya yellow. camel yellow
I recommend testing with a varnish over it before adding detail but overall this is a great yellow
According to the lore i would prime them black and then try to mix a slightly blue dark grey with lots of iron warriors (duh) and use that as a basecoat.
Personally i like vallejo black primer: https://www.amazon.de/Vallejo-Surface-Primer-Black-200ml/dp/B004BMZVMK - fuck amazon, i am just using this link because i have no idea where you are from ;)
Thanks!
They're at https://cults3d.com/en/users/Z-Axis_Hobbies
Mods- if this isn't ok, please delete. My intent with this original post was not promotion of a product, just to show off my own hobby progress. Only posting this link because I was asked.
GW do a cheap “flamer” airbrush but others are available. This is an all in one:
panthem Airbrush Air Compressor Kit, Multi-Purpose Air Brush Set with Compressor Dual Action, Cordless Paint Spray Gun Kit with USB Charging for Beauty Makeup Nail Design https://smile.amazon.co.uk/dp/B08QF81QV2/ref=cm_sw_r_cp_api_glt_fabc_ENRG0ENABXXJ5HHARY12 This needs a can of compressed air or a compressor:
Badger Air-Brush Company Basic Spray Gun Set https://smile.amazon.co.uk/dp/B0006MZPLG/ref=cm_sw_r_cp_api_glt_fabc_2XVJBBS8ZVJQNSW3HJTS
My current resipe for a fast yellow is as follows
Wraithbone spray
Mix 2 parts Indian yellow to one part water and apply all over as a wash
Wick away any pooling and let it dry
Give it a light dry brush with Dorn yellow
Link to the ink I use, I can usually find it at Hobby lobby and Michels https://www.amazon.com/Daler-Rowney-Acrylic-Artists-Ink-Indian/dp/B08JSC9RWD/ref=mp_s_a_1_4?crid=DT4JY8TOTQUS&dchild=1&keywords=indian+yellow+ink&qid=1631637604&sprefix=indian+yellow+i&sr=8-4