Forming your own kingdom can be a hassle or comfortable.
A hassle, meaning that you will be perpetually sucked into defensive fights. This might be the way you look to play the game, as it brings non stop action.
Comfortable, which means in my book that you can break free from the perpetual requirement of defending your kingdom. Warband offers the possibility of deleguation of war management by electing a marshall. Very useful as you can choose the size of the campaign and the way the campaign is led if you pick up the accurate lord as a marshall.
Before starting your kingdom, you must invest into certain operations to warrant the environment can sustain your goals.
Character: your character must be able to generate cash fast and this, in a restricted environment (looted villages, closed cities), whether you rely on trade or battle/loot to do it. Starting with 70,000 gold helps but you must make sure you can generate cash on the fly. Attrition can be punishing so be prepared.
Villages: defending a starting kingdom will take its claim. You need high relationship with villages both in your kingdom and in other kingdoms. If you rely only on your kingdom villages, anytime a village is looted means you cut off from possible recruiting. Getting 8 or 10 villages to support you completely allows fast and large levies, which makes defense of a starting kingdom easy.
Lords: you need friends in all sides. The reason is that as soon as you start your own kingdom, it is done at the expense of your former kingdom. Lords from your former faction consider you as an enemy, whether or not you befriended them. Right to rule might help to overcome this but it is easier to recruit outside your former faction.
The second thing is that they wont defect to you on ground you are friends. They need other factors to join your side. You need to target lords who no longer trust their liege.
Consistency of the faction: settling grudges have been reinstated. This said, it does not play a big part. You can recruit lords hostile to your ruling philosophy at no cost.
But at start, you will benefit from recruiting lords that go well together as you will be able to pair them.
Anytime you distribute land, give the castle to a high renowned lord and the associated village to a less renowned lord who will get well along the castle owner. This will lead the pair of lords to befriend each other and work as a unit. This reduces the probability they are singled out in a fight. The higher the consistency of the faction, the more the faction works well together. An important feature at start as you'll need all your lords to work on defending the kingdom.
So if you start with one city, three castles, you will need six lords to pair them to lead to an efficient defense of your kingdom.
Location of the starting city: if you locate the city at the crossroads of several kingdom, you will easily turn it into the wealthiest city on the (game) board.
