I have thought a bit about my ideas and would like to elaborate.
I imagine Victoria III as a game mostly focused on power struggles.
The easiest way to success and expansion is of course to start as the goverment of a great power, but I imagine that the most fun way would be to start as a oppositional movement.
All movements are influenced by following factors:
Organisation:
Ranging from "Decentral Organisation" to "State Party".
I imagine the folowing stages of development.
-Decentral Organisation: leaders more or less "pop up", their leaders are often charismatic; you as the "leader" have nearly no control over the movements directions but the movements message is simple and appeals to many. Many factions exist and will seldom break with the movement, but sooner or later they will want to centralise and found a party (or several).
-Loose Organisation: Time to choose a party name, acronyme and colour! Once you turn into a party it will be nearly impossible to turn back (I will explain that later on). You as the leader can influence and support other party members, which will be more likely to succeed you. Some members will break with you and found their own party. For example: you start as Socialist and turn into a Marxist-Socialist Party, some will break with you and found Anarchist or Christian-Socialist Parties instead.
You will get money based on the size of your party and your members socio-economic background. You can mobilize strikes and rebellions. You can spread your message through newspapers.
-Central Organisation: You can kick people out, but be careful, they will hate you for that. You have more power over who is to succeed you but you will also gain more rivals. Your rebellions and strikes will be more efficient.
-Cult of Personality: Most other parties will hate you, but your party will be loyal to you. If you are popular and charismatic your party will rise to new hights, if you are uncharismatic and unpopular your part will fall with you. This is only a option if you have a great leader, if you don't you shouldn't try this.
You can freely choose your successor, but he might be as popular as you and your former friends might turn against him, hoping to gain power for themselves. You can instead appoint a commission, which would produce a more popular, but probably weaker successor and would reduce you back to Central Organisation.
-State Party: You have to have "Central Organisation" or "Cult of Personality" and you have to be the rulling party. democracy will be abolished. Your ideology will become the state's ideology. All other parties will be outlawed but they might continue as underground organisations. You can try to surpress them and kill their leaders but that might lead to frustations in your own party. Factions in your party will turn into movements and maybe parties should you turn towards democracy again.
Monarchy
-Yes
-No
Voting System
Two different options.
-Proportional Voting System: smaller parties like this one, will reduce revolt risk but parties will split more often into smaller parties. Coalition goverment is usual.
-Plurality Voting System: The winner takes it all. The governing party will try to pass this, but will be near impossible if it is in a coalition goverment. Smaller parties don't like that and minorities neither. Parties will clinge together and seldom split but power struggles will be common.
Women's Suffrage
-Yes
-No
Suffrage
-Equal Suffrage: the name says it all. One person, one vote. Conservatives and monarchists will probably not like that, but the masses will.
-Census Suffrage: the rich get more represantion than the poor. The working class will hate you for this, but the rich will love you!
Chambers
How your parliament works.
-Lords and Commons: Only avaible as a monarchy. Nobles get their own chamber and will nearly always vote conservative. The working class will not like that.
-Two Chambers: You got two chambers, one for your realms regions. Centrists won't like that but large minorities will.
-Single Chamber: This is not a good idea if you have a multi-ethnical realm, but it makes laws pass slightly faster.
Goverment Type
-Parliamentary System: head of state and head of goverment are seperated positions. The head of state, may it be a president or a king, has nearly no power over how the country is governt. Monarchists, conservatives and charismatic leaders don't like this system.
-Dual System: Both the head of state and the parliament have influence, which leads to power struggles between these two. This works best a compromise to not upset conservatives to much and to keep the working class satisfied, if you are a republic. Ambitous monarchs will dislike this at first if you are a monarchy.
-Presidential System: only avaible for republics. Head of Goverment and head of states are the same. The parialemt is limited in influence. You will concentrate a lot of power but people might try to kill you because of that.
-Absolute Monarchy: Only for monarchies. The Monarch can ignore the parliament. Monarchists like that but most movement and parties will fight against this. Because you are a party leader you will probaly fight this.
-Dictatorship: You have all a lot of power, try to survive without getting paranoid and tyrannical. You can still have a monarchy but the monach will be as powerless as the parliament. Everyone hates you if you aren't very charismatic.
Freedom of Speech
-Free Speech
-Mild Censorship
-Harsh Censorship
... and other stuff