For roman soilders there is the main problem that the Roman empire existed for so long that almost nothing is true for all of them.
The uniforms they are always wearing in movies are probebly only really standardised like that for a small part of the empire, and even the not completly.
"The Complete Roman Army" is the best book on the subject.
Do you have some examples for these two, or maybe a link? I am interested in these subjects in particular.