To keep conformity amongst noobish players, and to make things a little fun, here are the uniform specs for rpg games hosted on my server. Team deathmatches and sieges will also use a slightly similar design and will be specific to each team. (Please note I will be using US Navy ranks as they are most known)
Each player will be assigned a rank upon joining the game. Ranks are not persistant with games on other dates, unless I see it as beneficial to the experience. You
CANNOT choose your own rank, and players abusing their rank pads will be removed from the game. As shown on the below picture, the ranks will fall under 4 categories for a general game. The highest being on the left to the lowest on the right. Each crew type can gain any rank, although only the Officer can be a Rear Admiral, and only Crew and Pilot can be commander. Both these crew types can be below these ranks as well. Here is a brief description of the ranks available:
Rear Admiral - The highest available rank in the rpg or team game, the rear admiral commands all other ranks and there can be only one per game. More often than not, this would be myself, although I will share out the rank on occasion.
Commander - The second highest rank is available to only the most dedicated and professional officers and crew members. They literally do most of the 'commanding' and will take control of specific areas in the ship such as flight, ship, deck and hangar. There can be up to four of these in a game (depending on server size)
Lieutenant - Lieutenants are normal crew members who have shown an exceptional aptitude to learning, obeying orders and being a good team player. They will command other ensigns in small groups, and will lead attack squads in battle.
Ensign - The lowest rank, but still high in responsibility. Any crew member un-assigned to a higher rank will become an Ensign. Working en masse, they provide all the labour, soldiering, piloting and operational skills necessary for a succesfull team. If you are an ensign, don't worry, you have a relatively easy role as you'll only be assigned one or two tasks, however you are just as important as any other player in the game.
In larger games, there may be assigned upper and lower class variances of these ranks, to add to depth and chain of command.
Now onto crew roles. You must follow your role and responsibilities or the entire operation may fail!
Officer - Officers reside in the control tower, and various stations throughout the ship. They are the epitomy in the command chain and command the other crew members to the best of their ability. Officer class hold the most responsibility and if you cannot control your crew you will be demoted.
Crew - 'Crew' is a pretty standard term for any crew member working indoors. The majority of players will fall under this job role as it is the most versatile.
Pilot - Pretty self-explanatory. Pilots are the guys that fly the planes. They are also trained in side-arm use and can be called upon to be used as make-shift soldiers in a ground fire fight.
Deck Officer - Deck Officers manage the deck operations, and primarily work outdoors or in the hangar areas. They are well trained in flight procedure and emergency protocol. A lot of players may fall under this role as well.
Hazards Officer - Crew trained specifically for emergency situations. They are specialised in bomb defusal (and placement), pyro-technicalities and other hazardous events. This will be the least used player role, but may be called upon in various scenarios.

Hope to see these in use soon! :)