In my SP experiences, Setup against AI to start learning:
Gold 200
ressource 125
supplies 100
The supplies setup is really important against AI to have it low. It will stop them to swarm you with 600 and more troops.
Always put your opponent in human setup. Choose the nation, don't take water nations, don't take Pangaea or Ermor (they swarm like any other AI).
You will see their starting position (cheating :S), you will choose their pretender (you are learning, don't give them the best... I usually find immobile pretender for them help you). Don't give them high bless. Don't spend all their god points.
Then after first turn, turn them to AI. They will be put in Normal mode (suck if you want more challenge later on) but give you the best control on those learning game.
I always generated my own map. Trying to put 1 on province nations setup because the 0 seems to give 15% of water provinces (damn).
Giving a high rugdeness (sp...) give more choke point. Mountain -> impassable.
Then, try to make virtual defense line at first turn. Identifies where you could have the minimum province to defend your country with a minimal provinces walls. Then rush to them and construct fort and PD at choke point.
Hope it helps,
Jourdelune
p.s. people are free to buy what they want, where they want. Only fascist culture tend to think the other way.