u/CanaryPitiful4719

Hi! I am super new to the game (20ish hours) so I decided to pick a small independent kingdom and focus on getting a handle on mechanics. I was independent for a while but then I lost some counties to my siblings because I don’t have a strong grasp how succession works. We were then both conquered in a matter of seconds by some foreign ruler and I was made a vassal.
I then was granted two new vassals by my liege and I immediately accepted them because it seemed like a way to get a leg up, but they immediately formed a faction and usurp me as the middle man. Their militaries were too strong and so I surrendered, but then they made me forfeit all but one county! Even the ones that belonged to my other vassals!
Ultimately I’m curious what other people would have done differently and what I should pay attention to in the future if I want to keep amassing land and get out of tribal government type.