Swordsmith Workshop

[Gilrandir]

Thanks for the tip. This way I can leave small force, mainly archer to defend the province.

Make sure that after 1205 you produce arbalesters. Archers run out of ammo too fast (for a bridge battle which may take quite alongish time to finish). And don't forget spears. A couple of spear units (pikes work even better), a couple of swords, one or two cavalry (to chase routers) and tons of range units - that's your Burgundy army for years to come. Unless you crush the French and expand westwards.

I am however very bad in tactics. Is there any guide for this?

If you mean battle tactics, there is A Beginners Guide to Medieval Total War which I mentioned. It contains (among others) tips on how to fight with different factions types (classified by religion). But those are only tips. Mastery is attained by practice. When I acquired the game I spent some years just fighting battles (custom ones, quick ones - you can choose any of them from the menu). But you may do this en route - in your campaigns.