Here is the SHIELD progression, from Man From UNCLE wannabe to super-spies, with the emphasis on Super.
Starting in their debut, in Strange Tales #135, Fury and all other SHIELD agents are in dark suits, as typical of 1960s office wear. There are military MPs standing guard, at different points, wearing OD green utilities or working uniform and white helmets, as you would find on an Army base, of the period. During the initial battles with HYDRA, we see that carried over a few issues. Then, when SHIELD enters into combat against a HYDRA group, we see Dum-Dum and other SHIELD agents in commando/paratrooper combat gear, including old leather football helmets, like those worn by tankers, in WW2 and airborne training.....
Dark blue is used as a standard color.
Later, when SHIELD is attacked by Mentallo and The Fixer, we see SHIELD agents and Fury in armored suits and helmets, also blue.....
A little later we get another specialty outfit, modelled by Dum-Dum.....
By this point, we have established blue as the combat color for SHIELD. Still have MPs in Army uniform, as guards.
Later, Fury leads a raid to rescue Laura Brown, love interest and HYDRA defector. The SHIELD field team is in new blue combat gear....
By this point, Steranko is on board as artist and, quickly, writer. He starts making small changes, like the field team. He adds another touch in the SHIELD support people in blue uniforms, instead of suits and shirt and tie...
Next, military MPs are replaced with SHIELD personnel, in their own dress uniforms.....
Note that Steranko (or the colorist) chose orange, with yellow accents. This stays as a color for the SHIELD grunts.
Within an issue or two, we see Fury suit up in a yellow flight suit, to pilot the Dyna-Soar craft. The color scheme is yellow, with orange accents, a reverse of the grunt uniform....
An issue or two later, Fury emerges in his black combat jumpsuit.....
Here, Steranko establishes what will be Fury's uniform, for the next few decades, with only a color change and mild changes/inconsistencies in shoulder holster and equipment pouches.
A few issues later, during the Yellow Claw serial, the suit is recolored dark blue....
During this storyline, Steranko introduces new supporting characters, like Val and Clay Quartermain. Clay is seen in an orange jumpsuit, with the same lines as Fury's blue suit.....
During the epic aerial battle between the SHIELD Helicarrier and Yellow Claws sky fortress, we see SHIELD agents board the sky fortress, like pirates swinging onto a merchant ship....
The SHIELD guys are in orange and during a later chapter, we see Dum-Dum in orange, as well as Clay, while Fury is the lone in blue. Val wears personally stylized outfits, basically bathing suits, or tank tops and tight pants and boots.
This is what everyyone would copy in later Marvel stories, through the 70s and into the early 80s. Fury was always in dark blue uniform, with orange shoulder holster and web belt and pouches, using his needle gun or a similar blast pistol. Dum-Dum varies a bit and is sometimes seen in a lighter blue, closer to the earlier SHIELD commando/paratrooper outfit, without the helmet. Gabe Jones usually appeared in orange, though sometimes in the reversed yellow jumpsuit with orange highlights, seen as the flightsuit of the Dyna-Soar. Other lower echelon SHIELD agents are also seen in the yellow suit. Clay Quartermain would appear in the Hulk, as part of the Hulkbusters, in his orange suit, with yellow gear. A SHIELD agent introduced in the early Spider-Woman stories is seen in the yellow, with orange gear.
Marvel wasn't consistent with things. There are some stories where everyone in SHIELD is in blue jumpsuits and other where it is only Fury and everyone else is in orange or yellow, except Dum-Dum.
OHOTMU standardized it as a blue uniform, with the color of the holster and gear signifying which division the agent served in, with white reserved for Fury...
That continued until the late 80s and Nick Fury vs SHIELD. After that mini, a new SHIELD emerges, with Fury and the new field agents in black uniforms and jumpsuits. I don't know at what point, but, we get to SHIELD back in the blue uniform, with everyone in white boots, holsters and accents, as seen in the Brubaker Captain America, Secret Invasion and so on.
The Nick Fury telemovie had Hoff and the principals in black leather, Dum-Dum and Gabe in suits, Clay Quatermain and SHIELD agents in navy blue utilities, with a black SHIELD armband, similar to the type that MPs wear (hooks onto an epaulet, then wraps around the bicep and fastens with velcro). HYDRA wore grey "urban camouflage" utilities and mesh facemasks (of a type sold in surplus and hunting catalogs as camo netting). In the MCU, Fury is in black leather and Colson in a suit, but in the Avengers film we finally see SHIELD troops in blue utilities and then people like Maria Hill in the blue jumpsuit. The tv show mixed suits and civies with black or blue leather and combat gear. The Avengers, Earth's Mightiest Heroes cartoons had SHIELD and Fury (depicted as African-American, as with the MCU) in the blue jumpsuits and white boots and gear.
Like I say, I like the blue jumpsuits, though not the white boots and gear. No para-military organization is using white, in the field, unless they are in snow. I was never keen on the orange or yellow versions of the suit and Marvel wasn't consistent with it, until OHOTMU standardized it. The colors are too bright for anything other than safety gear and the MP uniforms looked ridiculous.
