Sorry, Von, but you're going to have to wait a little bit. My home comp crashed and until I can get it up and going again I can't really do much of anything. Don't worry though. I am on it and will have the guides up ASAP.
Until then I can guide you with text as best I can using this Color Chart. Now this is just based off of the uniforms as shown in the C-Store and what few lighting tests I was able to get done last night before my comp crashed.
The colors should be ordered like this; Red B2, Gray B12, Gray B10, Gray B12 for most of the uniforms. Substitute Red B2 with Gold B1 for Operations and Blue B2 for Sciences. Color pant stripe or deco to match. Use Pants 01 with Top 01, use Pants 02 with Top 02 and 03 and use Pants 04 and 05 with Top 04 and 05. Use the belt only with Tops 02, 03 and 05. The others have details that the belt would obscure.
Hope that helps for now. Like I said, I'll have the image guides up as soon as I can.
Just out of interest, has anyone given any thought to what 25th century Starfleet Marine Corps uniforms would look like? There doesn't appear to be any really official source, soft or otherwise, which details them, and when searching for examples I saw everything from regular Starfleet uniforms with a light green-olive colour replacing the normal division colours, to some horrifying amalgams of DS9 uniforms, Enterprise uniforms, and real life American Marine Dress Blues(*shudder*).
I suppose that, ideally, SFMs would wear armour, but as the game's armour is A: godawful looking and B: colour-locked based on class, that's not really an option. I wasn't able to come up with anything satisfying, but I only spent a half-hour on it, perhaps you chaps have some ideas?
Its not a huge stretch to imagine it exists in at least some form. Specialized shipborne planetary assault troops would be a requirement to maintain any semblance of defense against hostile powers for any star faring nation.
I am now in the process of collecting as many images I can of Starfleet Marine Corps uniforms. I've found some really good ones. I plan on creating a mock-up for each of the Standard Duty Uniform, the Combat/Mission Uniform and the Dress Uniform. These will be added to the Soft Canon/Fan Choice section when they are finished.
A mock-up of the MACO uniforms from Enterprise is also in the works.
These have both been scheduled for addition after the Jupiter uniforms, which I plan on having up by next week.
there's never officially been one mentioned in canon, but it's been recognised in fanon for years
That's not completely true. DS9 made a couple passing references to "ground troops", and the "Siege of Ar-558" gave the implication that those troops were better trained in ground combat than most Starfleet.