The first thing you do is earning some money, level up some levels.
Hire mercenaries, use them to level up.
The best unit to hire would be mercenary horsemen, then upgrade them to mailed knights, you can also hire mailed knights directly.
Gain renown, get over 150 renown and you should become a vassal for a faction, rais leadership so you can have more soldiers in you party.
The marshal of the faction will call on you to join an attack on a faction.
And when you atleast reach level 20, you should handle pretty well.
Remember to focus on raising attribute points on 2 weapon types, I usually only raise 1-handed weapons and 2-handed weapons, because those weapons suits me best, and I use some on crossbow for sieges.
You should handle pretty well, but in the start of this mod, you should stay on your horse, you are safer there than on foot. Also a good tip is using a polearm to deliver a couched lance attack, you will surely kill them instantly if they are not blocking.
If you dont know how to couch your lance, then do this, buy/loot a lance/spear, ride toward your enemy, dont click on the left mouse button to attack, just keep riding towards your enemy, press "R" to enter 1st person, aim your polearm and ride it through your enemy.
Now that you are in good level (lvl 15++) and a vassal of a faction, you should also focus on raising you training attribute, your troops will rank up faster then.
Also if you have a bad armor I suggest you do this.
Go to Cork in Ireland, enter the city, you should start outside the gate, head towards the armorer, when you reach the armorer turn left, head towards the church at the end of that street, now you should stand in front of the church door, looking at the door, turn around and you should see a pile of hay, head towards it and look at it, it should say chest and you might see a little part of the chest open it and you will find a good armor.
Ahh, now my hands are stiff because I wrote to much, hope it helped and I hope you enjoy the mod.