I'm new to Vampire: the Requiem and I would like to write my own chronicle but I don't know where to start. Where can I get inspiration and how can I structure the campaign/chronicle so it's cohesive and feels true to the setting of VtR?
I don't have experience with Requiem. But I have a big load of experience with Masquerade, and general advice constructing a chronicle must be the same.
There are a lot of approaches building a chronicle, but they always start the same way: a simple idea. Like "a weak prince contested by several elders" or "a conflict with werewolves" or "vampires in competion for the love of a single mortal" or even recreate the feeling of a book or movie. So, the first thing you need is that idea.
Then, as I said, you could use different approaches to build the setting. I am going to tell you what I did for my last chronicle.
After I had a first idea of what I wanted for my chronicle, I made a list with the most common themes in vampire literature and films (lust, violence, death, immortality, humanity,...) and I told my players to choose which were more appealing to them. This way I had an idea of their expectations. This isn't always necessary, but I didn't have much predetermined, so I let them set some themes.
Then I added my own, what I wanted the chronicle to be about. Many of them come from the first idea. Also, I visited TV tropes to learn which tropes I would like to insert.
Sometimes is difficult (at least to me) to differentiate themes and ambient. The ambient is for me like some more subtle theme that it's still present in all the setting. It must be underlined on all locations and characters descriptions.
For example, if your ambient is madness (which could also be a theme), all the main characters would have twisted minds, the minor should be desperates, the locations should have loud sounds and consfusing colors, barting dogs and such.
For me, the centre of the chronicle are the characters (NPCs or PCs). So, once settled ambient and themes, I start with characters.
It is often better to start with PC (although at this point you sure would have several NPCs in mind, just try not to concrete them too much). This way, you can build the setting around them, opposed to build first the setting and then try to insert PCs in your already defined world. Remember PCs are the protagonists and the world rotates around them. Pay special atention to the Backgrounds, as they are the PCs' connections to the world.
Once you have your PCs, you can start concreting your NPCs. Make connections with the players (sires, friends, rivals,...). Add the ones you also need to treat your themes, and to fulfill your first idea. Make all NPCs of the characters background: they're not only a resource, they're plot seeds.
When creating NPCs have always the ambient in mind.
Your chronicle will have main plot.
Also you will make secondary plots for treating the themes you came about. The best way to make use of themes is having plots based on them, rotating them, and repeating several times.
You will also need to make personal plots for the characters. Base them on their character personality, history and motivations. Listen your players and you will get cool plot ideas. Try linking them with themes.
You will need to make new characters for some plots, or fit the ones you have into the roles the plots demand.
The prelude serves as the presentations of the PCs. Against the books advised, I don't always make them about the embrace. As in vampire fictions, a character prelude can start with him being a vampire. Three things are important:
A chronicle, like any fiction, should have an end. Better to close themes and plots than let the chronicle die by boredom.
I can't give much advice on this, since I many times fail to follow this rule.
And that's all I can think of without getting in much detail. Hope that helps. And read the books, there are a lot of helpful advice.
In my core book, starting at page 17 they have a list of inspirations/sources for Requiem and it's fairly extensive. If you watch/read even a smidgen of the titles listed, I'm sure that the ideas will start pinballing around.
Without more information about your table and your own ST style I can't really give you much more than that.
You can consult a Chronicler's Guide for general guidelines, examples and story seeds.
A point, in addition to the very good points made already.
Limit Presence of other Supernaturals
with regard to "so it's cohesive and feels true to the setting of VtR?"
I strongly encourage you to limit the use of other WoD supernaturals. They can dilute the feel. Each line, generally has all be based covered already (roughly). Eg you don't need werewolfs -- you have shape shifting aggressive Gangral. You don't need mages -- you have circle of the crone, to do mystical things.
If you must have other supernaturals, know exactly why you have them Don't say "It is world of darkness, of course there are werewolves and changelings and mages and geists and giant corporations harvesting people for parts." Instead pick what you want for the reasons you want.
For example: "I want the vampires to have a reason to all work together, so I want them to be at war with someone. Its got to be a supernatural cos I want the war to be secret. It could be other vampires, but there are issues because why are vampires suddenly moving in on there turf? I will have a Freehold of Changelings -- it is reasonable that they only just realised the other existed, and they compete for resources like secret meeting places, and mortal political power."
This extends beyond just supernaturals to an extent, to all factions that exist. Make sure you know what this faction is about, and why it is in your chronicle. "The Carthan's are basically Terrorists in this city. They are there (as a plot point) to ensure that the Invictus prince, is paranoid about going anywhere without guards."
Decide what you want as a Theme
Know your them. Know what you want your players to be thinking at the end of the game.
A good example from Hunter the Vigil is: "Hunters are the True Monsters after all.". With a theme like that you know when designing your campaign to focus on luring the player characters in to mosterous acts. Eg Buring down the old persons home to kill the vampires hiding within.
Now themes for Vampire, might be
Know what you want.
Don't write a Plot, write characters.
There are 3 ways to write a RPG story. (There are probably more, but you see the general area this is going)
Write a series of events that happen to the players, a quest line more or less. If you are writing this you are writing a story.
Write a series of events that happen at places. Eg The target arrives at his fortress, bandits attack the village. This is like a timeline combined with a map.
Work out what every major NPC wants, and what resource they have to achieve it. This is what I recommend for vampire (and Changeling, and any other political game). Instead of saying "The Regent of South Port domain is going to attempt to assasinate the prince, so he can take his place." say "The Regent of South port. Goal: Become Prince. Reason: Thinks prince is weak. Resources: Cathian Ally's, Large herd. etc" You can then work out what he would do, in any situation. So now perhaps you see that a PC has gotten beaten up in South Port, what is the regent going to do? Does he finish them off because they would support thing Prince? or does he save them to gain there loyalty?