1) Garrison ur Cities with the LOWEST upkeep units.
e.g. archer militia has lower upkeep than spear militia.
During my Milan campaign, i only realise that spear milita has a higher upkeep than crossbow militia after i had 1/2 the map under me. I used only spear militia to garrison my cities. imagine how much $$ i can save if all had been crossbow mlitia.

2) Plan your Fortress and etc.
I usually have a Fortress "guarding" an area or choke.
e.g. For British isle, i only have 1 Castle there, the rest are cities and will be converted to cities.

3) Plan your Sea territory.
I disagree keeping 3 ships at each dock. This is a waste of units and $$$.
Always re-draw ur sea territory when u took over a continent.
e.g I have the british isle, the sea around it is my interest. Getting a stack or 2 to choke the important places or area.
Then i have the area from the british isle to spain and portugal. The area is extended there. But i also only need 3 or 4 stack of ships. If i choke the british isle and the desert crossing at the south well, i do not need to defend the top left of the map except for pirates. So only need 2 stack to chock and 2 more to chase away other problematic navy.

4) Plan ur garrison stacks and invasion army stack
garrison stack does not equal to invasion stack. For castle garrison stack, i only have heavy horses to kill of rebels stack popping out. For invasion stack, mostly are veterans. How u wan to swtich between both stack is up to u.


With enough $$$, nothing can stand in ur way. e.g. I was playing with the scots. Then mongols can and sweep from the west towards europe. I had most of europe and i cant seem to find a good tactic to solve the mongol problem. So i just spam stacks and stacks of anything and throw at them with auto-resolve. Starting part seems furtile but turns later the mongols are overwhelmed.