I don't know whether SeV's gonna support this idea or not, but scripting this will make the server very unique and will make the clans a thing worth to join. I do suggest reading the whole topic, suggestions are welcome.
First, starting with the colors.

Clans colors.
Umbrella Corporation and STARS. Who leads what is up to SeV, the colors should be;
UC:#16a718 (Green)
STARS: #FF1493 (Deep pink) or #a7d5fd (a darker shade of alice blue) (could be #A7D5FD)

Now that we're done with colors, we need to find a way to get players to join these clans and keep the password secure. In my opinion, we don't even need a password. No one likes their default color if they get to join a clan, so we can;
Create a command for level 4+ admins to set clan leaders, that is /setstarsleader (ID/Name) and /setucleader (ID/Name).
After you're set as a leader, this message will appear in a golden color (FFD700 is the hex)

Owner SeV (0) has given you S.T.A.R.S/U.C leadership rights, congratulations! Use /ccmds to view a list of commands.

After you're set as a leader, you can 'force' set members into your clan. You're not supposed to go around setting random players as clan members, it would be against the rules! /ccmds will show a menu that lists the clan commands.
Use /ccmds and a message would appear;

You're now viewing a list of clan commands.

/cclass (Clan classes)
/setmember (ID/Name)
/setmemberrank (ID) (Rank number)
/kickmember (ID/Name)
/cchat (Clan chat)
/resign (Resign as a clan leader) (Will show a confirmation message that says; "Are you sure you want to resign as S.T.A.R.S/U.C leader? Yes/No")


Clan ranks:
To be used with clan classes;
Leader - ID 5
Assistant Leader - ID 4
Elite - ID 3
Veteran - ID 2
Rookie - ID 1

Clan-Classes:
Clans are just a tag right now, and they seem very bland. We can spice them up a little bit.

UC:
Rookie class: (U.C Corporal)

Skin ID: 171
Weapons: Desert Eagle (100) - Shotgun (50)
Immunities: Default Infection
Skill: /heal; A somewhat stronger version of /heal, can heal a player by increasing his HP by 100
Health: 100
Armor: 50

Veteran: (U.C Medic)


Alternates between these two.
Skin iD: 165 and 166
Weapons: Desert Eagle (100) - SMG (300)
Immunities: Default, mutated
Skill: /givepk (Give pain killer), it will increase a player's health by 3 for 10 seconds, a total of 30 HP can be regained. Can be used every 15 seconds, you must be next to a player to use it on him.

Elite: (U.C Scientist)

Skin ID: 285
Weapons: Desert Eagle (200) - M4 (250)
Immunities: Default, Mutated, Witch
Skill: /acure (Aqua cure). A very strong ointment that can heal many wounds. Can be used every 30 seconds on another player, it restores that player's Hp by 50 and cures any infection he has.

Assistant Leader: (U.C Captain)

Skin ID: 3
Weapons: Desert Eagle (300) - M4 (300) - Shotgun (100)
Immunities: Default, Mutated, Witch, Advanced Screamer
Skill: /acure and /givepk

The leader himself does not have a class, it would ruin the immersion. Why, you say? Let's say I have 3000 XP right now. SeV sets me as UC leader and I suddenly become able to access a class that is as strong as a 250000 XP class. That's not fair now, is it? The leader himself has access to all of the other classes, but doesn't have a personal one.

I'm making it work like this;
U.C is more like a clan for medics and those who assist in combat. They have strong weapons and strong medicines
STARS is pretty much a clan for soldiers who supply weapons. They have strong weapons and strong items that you can use.

This is still a WIP, gonna submit it now and go to sleep. I'm asking for your feedback, what do you think etc.

Its a pretty original idea but i dont think sev is going to accept it.
Also its not a good idea giving the leader access to the /setmember command . The leader wont invite someone just because the doesnt like him and thats not fair , its better with the original way of recruiting (posting on forum).

No, no. Of course the guy still has to apply on the forums before being able to get set as a member tho.
USMC is gone, Bulls. ;l