Blitzkrieg tips

I need help about this strategy Blitzkrieg.
is it worth to defend city? because i play in whole world games but i cant defend well so i need some tips.
I capture city but i don't know how to hold so long and when i get some capital i can't defend it well i always put more inf like 50 but they lose from 30 stack unit.
And which units to buy?

Anyone know some tips about this strategy?

Continuously attack until there unit stack are down the drain, the rep the benefits

Wall you cities before attacking.

Keep on the offence.

Keep your transports in a network so that when an enemy attack you can move about easily.

Use every militia for attacks.

As soon as you attack the walled cities bring down the wall and replace with militia then move on.

Wall big stacks.

Attack everywhere!

Use air transports to boost your range.

Use only militia for defense.

Use your network of transports to move militia from Spain to Iran in 1 turn.

Never stop expanding.