Kreigar said:
How can you take a castle in a faction that loves you? If you're friendly with everyone, how can you even attack the castle? Also, won't all the lords of that faction hate you once you attack one of their castles?
I think that recommendation was that you try and take a castle that's close to the border of a faction that likes you. This reduces the amount of armies you'll be fighting later when you'll be under huge siege from the entire angry factions troops. So don't attack or annoy the friendly faction, just take a castle close to their border.
Kreigar said:
And do I need to take a castle in the faction I want to get most of my troops from?
This is unwise, because (I think) you'll lose the ability to recruit from that faction except from owned territory. As I said before it's easier to take castles close to the border of a friendly faction both because they are less likely to attack you and also because you can get replacement troops from them.
Kreigar said:
I just need some guidance on how to select a castle to start my kingdom and the exact methods I can use to go about attacking that castle.
Selecting a Castle:
1. Is it close to the border of a faction that you're friendly with and/or getting most of your army from? This is good.
2. Is the method of assault by ladder or siege tower? You really, really want to be fighting ladder battles.
3. Are there that many troops in it? The lower the better.
Attacking a Castle/Town:
1. It helps a lot if you can use a bow/crossbow. You're way more accurate than even the best NPC archers in siege battles.
2. Amass a lot of good archers. I personally like Rhodok Sharpshooters, but try others if you want.
3. Siege a castle with a ladder battle and attack!
4. On the map starting get everyone to hold position and then have your infantry run back to the back of the map (Retreat 10 paces or something multiple times). This avoids them taking casualties during the next phase.
5. Order your archers to spread out and start firing. If you have a bow or crossbow aim for the enemy archers first. If your archers kill rate is low consider moving them forward although if the enemy still has a lot of active archers it's usually not worth the casualties.
6. Once you or your archers run out of ammo retreat.
7. Repeat steps 3-6 with the same castle until there are very few enemies left (this is up to you depending on the size of your army)
8. Storm the place with your infantry! Good luck.
If you succeeded congrats you're got your first castle. Don't love it too much though, a 200+ war party is probably going to come your way very soon.
In my game I use ctrl-h, ctrl-t (truesight and teleport;you can't really trust your lords to defend your territory that well) and ctrl-x (for money) liberally. You might also want to consider changing the amount of renown needed for an extra party slot. I am level 24, have a 151 party limit and own 17 settlements in Swadia and Vaegir territory. If you end up having to fight a siege tower battle then your troops do nothing until the siege tower is in place while being covered in arrows. This makes doing step 7 a lot harder. I would recommend avoiding them until they're the only resisting settlements left and then take along a big army and prepare for losses.