[Baalz]

Yeah, the thing is suggestions for SP games basically break down into two categories.

1) General strategy. You seem to have this down and suggestions you get are going to be along the lines of tweaks, not overhauls. You've laid out a very viable EA Mictlan early game strategy. Unfortunately, playing against the harder AIs means you're not playing on a level field, you can't just be better you need to be much better so you can kill off many times what you lose just to push even. This unfortunately means playing a good game is often not enough to win, particularly if you get placed in a bad position.

2) Tricks to exploit the AI - use a lot of PD for no purpose other than to fool it, create thugs that the AI can't cope with, etc.

Unfortunately category 2 is really what you usually need to do to fight against multiple harder AI's - by the time they team up on you they just field too many troops to "fight fairly". This is unfortunate because once you learn a few tricks that the AI just can't deal with it does become way too easy.