I have, as many of you have seen, already stated my stance to this before. But for the record, I'll state it again:
Citizens
I am a firm believer that Citizens are the absolute number 1 priority in City RP, to the point where I think that any addition or change to anything in the server should be met with the question of "Will it make Citizen RP better?" So many servers fail to realize this, even if they say that their Citizen RP is good. It makes sense though, why wouldn't the default faction, that almost always has the vast majority of players, not have the most attention?
What this means in practice however, is that Civil Protection, Resistance, and any other sub-faction (save for maybe Vorts, but I'll touch on that briefly) should exist only to prop up Citizen RP. More crazy ranks won't make Citizen RP better. CP's practicing their firearms at the range won't help Citizen RP. Rebels hiding in some base in the sewers won't help Citizens. Administrators doing office work doesn't help Citizens. What do I think we should do in these scenarios? Simple, make them not do that. If they want to isolate themselves from the rest of the server and leave Citizens to diddle their dicks in the streets with nothing to do, then why do they exist on the server?
I do believe these alternate factions can have characters, those that can be developed and grown, but these characters need to do so while interacting with Citizens.
Other things should also involve Citizens to the max. Businesses, especially, are wonderful for Citizen RP. The CWU may make more sense (debateable), but having Citizens run Businesses means that you are giving more for Citizens to do. It unlocks so much more for Citizens to do that normal CWU might not, while also not forcing Citizens to have to be loyal to the Combine in order to do it.
The end idea for Citizens themselves, beyond just having all the factions cater to them (as they should) is to give Citizen characters choices, progression, and content. A majority of HL2RP players believe that Passive RP just doesn't work, that it is "boring" and that "Citizen faction just needs more action RP." I think Passive RP can work, it's just that servers never give Citizens the means to do so. Often times, servers who tell Citizens to "make their own RP" are just ignoring the issue in that Citizens don't have the means to make their own RP. By giving them choices, you engage them and make them interested. By giving them progress, you make Citizen players invested. By giving them content, you are ensuring a system and reward for those players.
That is what all things among the Citizen faction itself should be based around. Citizens should be able to choose the path they want to take. Business owner? Working in a business? Rebel? Criminal? Aspiring loyalist? Underground market lord? Corrupt loyalist? The choice should be there in the first place, which ties into content. Content exists in the form of a system. A good business system means that a player not only can run a business, but they also need to work to do so. They need to be competitive. They have to work against other businesses and offer the best prices. A good loyalist system sees that they aren't just farming points, but actively have to appease those above them to rank up in loyalty, and thus gain new advantages. Rebels need to actually be stealthy, and show that they can help Citizens in order to gain more. It's all about giving them a path to go down, instead of leaving with them with nothing and wondering why people are saying the Citizen faction is so boring.
Civil Protection
Civil Protection are the obvious antagonist of City RP, and they should be treated as such. As before however, they exist to be the primary antagonist of Citizens, not the rebels. But there are huge caveats that should be in play for Civil protection in how they act. For one, there seems to be this really shitty idea that ultra realism must be obtained, and that Citizens "must be punished and oppressed to the fullest extent to really nail that epic 1984 feel XD". This doesn't help Citizen RP. It doesn't help any roleplay. This kills it. Civil Protection are an invasive antagonist, yes, but this is Roleplay first, and then atmosphere second. Civil Protection have always had this bad reputation at barging in at the completely wrong time and interrupting RP for assinine shit. Judgement Waivers are the epitome of this, where Citizens have to drop what they're doing and look at a wall for 30 minutes while everyone complains in LOOC.
Civil Protection need to have an OOC lense of "Citizen RP first, Civil Protection Duty second". Maybe they shouldn't pull a random raid when some shop is full of RP. Maybe they shouldn't just go up to Citizens in the streets and tell them to isolate. What they should do, is act as an instigator of RP, and a threat towards those who warrant the Civil Protections eye. If a Citizen isn't doing anything, perhaps they can be stopped and questioned, maybe even pulled in for a random interrogation. This is good because it is giving Citizens who seemingly have nothing to do, something to do. On the other hand, they act on what they are given. It is okay to interrupt a scene if they know someone within it is wanted, or is carrying contraband.
Civil Protection against rebels should not be the main focus of City RP. That's not to say it can't happen, but it shouldn't be the objective of Civil Protection. The exception to this is when Rebels are being actively isolated and hostile towards Citizens. In these instances, Civil Protection are a very harsh, and violent tool that can be used to squash out Insurgencies that aren't helping Citizens at all. This encourages rebels to be more stealthy, instead of hold up in one location. I'll touch more on that later.
In the end, it ties back to Citizens. CP are focused on acting as a threat to Citizens, but not their Roleplay.
Rebels
I have always catagorized rebels into two styles: Incognito, and Insurgency. I believe Rebels should be very hard to tell apart from Citizens. This is a City, not an uprising RP. In doing so, they have to blend in with Citizens, and thus are actively helping Citizen RP, tying back into the Citizens first idea. Where Incognito and Insurgency Rebels come in is how they act.
On one hand, you have Insurgency rebels. These are the rebels most players have likely seen in City RP. They are heavily armored, carry around guns, run around the sewers, hide in their base, and their only interaction with the surface is simply going up to gun down cops or make an explosion. This does not help Citizen RP. It simply forces the Civil Protection's hand and makes them go on a witch hunt while Citizens have to move indoors and stop their RP because some character they barely ever see if at all decided to use their scripts and gun a bunch of CPs down. They aren't realistic, they aren't good for Citizen RP, and they barely have any place in the server.
On the other hand, you have Incognito Rebels. These are the rebels you don't see, but for the right reasons. It's not that you don't see their characters, you just don't see that they are a rebel. That's because they choose to blend in, and do what they need to form a Resistance among the City, not just some unrealistic army of armed rebels that suddenly pops up from the sewers. These Rebels have to blend in among Citizens, and by doing this they appear to be just like Citizens. They walk among them, talk among them, and more. What this does is creates an environment where you have characters who have secret intentions, and have to influence the Citizens to their side. They smuggle in supplies not for themselves, but to gain the approval of the populace. If they need an operation done, such as a store robbed or supplies delivered, they get a Citizen to do it, not themselves. What this does is put the Citizen first, not the Rebels.
This is where the Civil Protection "tool" comes in that I said earlier. You can discourage insurgency rebels by making their practices easy to spot. Rebels stockpiling tons of supplies? Have Overwatch detect a pattern of movement through their perimeters and send CP to search and mercilessly eliminate. Rebels hiding out somewhere? Have a team sweep the sewers with no warning, and root out the resistance until they are no more. Believe every report Citizens give about rebels somewhere and pursue. The idea is to make the CPs absolutely intolerant of rebels to the point where they will seek them out. This makes playing rebel a matter of stealth, not power. Their power alone cannot take on the Combine, and a stealthy rebel will naturally avoid the Civil Protection much better than your insurgent rebel. By doing this, it encourages good Rebel RP that helps Citizens, and discourages shit rebels that isolate from everyone and circlejerk.
Vortigaunts
Vortigaunts have been given the shit stick for a long time in City RP. Servers have this reputation of just throwing them in a cage and then bringing them out so people can "Ooh" and "Aah" at the Vort before they get beat and sent back to the cage. Enslaved Vorts have a really easy fix, and that's just making them second class Citizens. They live among Citizens, but with additional duty. They work harder, can never achieve loyalty, and suffer from prejudice in which they are treated as lesser beings than humans. They are bossed around, may be banned form certain stores, and more, but what this does is place Enslaved Vorts among the Citizens. It's a very simple, quick, easy fix that isn't done often because they aren't labelled as "Citizens."
Freed Vorts on the other hand are tricky. You need them to interact with Citizens somehow, but you can't just have them on the surface all the time. This is why certain areas on the surface should be patrolled less than others, so that Freed Vortigaunts can move to the surface. Perhaps they can also put on fake, deactivated collars that make them look like an Enslaved Vort, in which they can freely leave and just go. What we don't want are freed Vortigaunts who simply stay in the sewers all day. At that point we just have Rebel Insurgents but aliens, which we don't want.
Administration
Administrators and their teams should only exist to carry out RP that is on a larger scale that normal Citizens can't do, and that which is unlike the CP to carry out. Work cycles, broadcasts, etc. They should only exist to do this for Citizens, not for themselves or other entities. If an administrator is not doing this type of stuff, they might as well be circlejerking up in their office.
Conclusion
There are many other things that can be talked about, but this sums up what I believe are the most important bits of City RP. There are other things that should be done to better the chances of a successful server, but my point has been mostly made. Let me know what you think, whether it be negative, or positive.