[Nick_K]

The AI shouldn't get an advantage in gold or resources on average difficulty AFAIK. In fact, they often have bad scales - if you have, say, order/growth/productivity then you should have a considerable edge.

The AI does often have bigger armies though, because they build more 'chaff' troops. This is actually a weakness though. It's been toned down since doms2 though so AI army composition isn't terrible any more.

Starting conditions can seriously affect your income. Most maps have areas with quite a few of the very high-income farmland provinces. If you start in an area of forests, swamp, mountains or wasteland then you can end up with much less income than an AI with lots of these provinces. The reverse is also possible.

Are you using mercenaries? These can give a huge boost to early expansion. The AI always bids the minimum necessary to get them, so by bidding 1 or 2 more you'll always win. This could be considered a bit of an exploit, but dominions is actually quite a hard game for beginners so I'd recommend it!

As for nations to avoid... van/helheim are tough although I think the AI does not take advantage of them anything like as much as a human would. I'd avoid the sea nations if you're on the land on smaller maps. Late age Ermor is also quite a challenge unless you know how to deal with them. It took me a loooong time before I could beat Ermor in Dominions 1.