Yeah blast from the past, long time since I played and I don't remember the differences between Imp I and II very well. It will definitely take a few plays to get used to building up your country efficiently - each early turn is pretty important.
You need to maintain a balance between hooking up resources by rail, building up a merchant fleet, trading, improving your workforce, and then building up an army and navy to whack things.
Pick a couple of minors generally not on your continent with resources you can use and trade like mad with them, keep checking to make sure you're the best trading partner. On the political map their color will get greener and greener, and eventually you can ally then incorporate them. Minors on your contintent, just conquer at the appropriate time.
Learn to win the battles even when outnumbered - artillery pretty much rules, the rest is to keep the infantry off your artillery. The scout type guys are good for moving first and soaking up enemy artillery shots, then you move yours into range and blast theirs. NEVER use Otto (automatic) for battles, the AI is awful. If they have a big force, sometimes you will have to attrite and retreat.
Keep the specialists working, especially the resource finders (prospectors?) - getting iron and coal is vital, and they will become the critical commodities that you will want to trade then eventually conquer for.
Heh, I'm more than half tempted to dig out the CD now...