i find sieges very easy to win
Just build a ram if your RAM is destroyed before getting to main gate you can retreat or scumsave
siege towers are also good cause defenders will try to get down the wall (broken AI) and your archers can pick them easy
When you are in siege mode check if they are building catapults or balistas, balistas never breaks RAM if they get 4 catapults you can get 1 or 2 trebuches to kill the catapult before going to battle mode
Try to kill archers on wall/catapults, when your RAM destroys the 1st game rush inside and kill the 2nd gate as soon you can then is just a bloodbath, sometimes the defenders even came out of the castle lol
Make sure you have alot of archers and shielded footman, no recruits and you can win 1:1 ratio