[Nick_K]

You don't actually /need/ research t beat the AI. If you're being beaten in the early game then consider investing less in research. You also don't need more than pd10 except in border provinces.

Try to keep the number of border provinces low. If you have 7 provinces and, say, 4 of them border enemies then you'll have a hard time concentrating troops in every one of them. At the beginning of the game pick a couple of bottlenecks and expand quickly to them and then slow your expansion. Of course, you should always have an eye on the next target. Dominions is a war game rather than a civ-building one so I'd recommend continual expansion.

Make sure you use mercs. They provide a big early game boost. Bid 1 or 2 more than they ask to be sure you get them. Most mercenary groups are well worth buyign at the beginning of the game.