So we can have show our body armor and we can show our kits but we don't have any type of headgear? Protective or fashionable otherwise unless you count the different types of visors that can be worn. Having protective head gear such as helmets or for off duty some form of hat would be awesome in certain situations for example: My Gorn on the KDF currently is wearing a very dark uniform for special operations and being covert because of his green skin he sticks out like a changeling who can't shape shift very well.
Helmets I think would be more of a KDF type thing since in the shows they always have some form of armor (although not helmets, yes) where as the federation don't tend to use that and just go out in the little uniforms and pray there name is in the title sequence so they don't die

What I propose is:
- Protective headgear for both factions. Something futuristic that looks military like, but isn't silly like old roman helmets with the furry thing on top.
- Hats for off duty uniforms or on duty for federation since helmets isn't really there style (although to date I don't remember seeing any kind of "helmet" in trek, except for short sequences in TOS ERA and Bajoran's and Guinan). This could be just a simple baseball cap like in Enterprise:
http://memory-alpha.org/wiki/File:Archer_in_cap_and_desert_attire.jpg which was used on various away missions. The hat could be fixed with your ships/characters name.
These are just some simple additions I came up with, I guess others could easily expand on this
Comments
BTW - They did have hats in the original TOS pilot (here) and lets not forget the Niners ball cap (here) from DS9.
Well yeah like I said I don't exactly recall every moment they had some form of headgear but I knew there were some. Yes the head shape and head appendages of different species would present an issue I thought of this but not exactly sure how to overcome. For example Gorn's head is longer so helmets would need to be longer around the front and Klingon helmets need to be bigger at the top to account for their ridges.
Its tricky to implement defiantly but It would work fantastic if it can be done.
Well.... possible i suppose, but not practicle.
Not even all the clothing options work properly with all the aliens and bodies, as well as hairstyles.