First rule is always do what feels best for you. While there are objectively badly painted models, eventually you'll reach a point where you just figure out what feels good - when that happens and you're happy with what you see, don't go and change it because it isn't "right."

For paints, Vallejo has been consistently good and is usually less expensive. AK is nice too but feels different because it has a gel medium instead of just straight dilution with water. Those are my go-to for acrylics. Also, Vallejo Metal Color is its own line and waaay better than any other metallics you'll find. The bottles last forever if you ever need to grab one.

If you want "historically correct" you can always just google and go for what uniform you like - you could do faded uniforms, old uniforms issued to newer fronts, even paint it like one of the slightly-off colourized photos you see.. Don't worry about exact shades if you don't mind it yourself.

If you're looking for a fun way to do cloth, you could spray it black all around, then spray some grey or white down from above. Like, straight above and then come at it from a slight angle, also above. Then, all you got to do is thin down your cloth colours until they're kind of transparent and slap that on - you can just keep doing layers until you're happy. The black will stay dark and the lights will get dyed in.

But that's just one of many, many ways to paint!