Notes from the forums:
The main constraint is workforce, as to create states in African colonies and elsewhere you need to try to engineer a Portuguese majority in one province. Conquering negative prestige but populous civilized territories in Latin America really helped to provide labor to broaden the industrial base.
Some other points:
- Stay close with the UK. A guarantee from them is often better than an alliance as you have more freedom. If they get to dislike you, they are easily able to take your colonial possessions away, or let the French do it.
- Colonize all the coastal provinces north of Mozambique and then work inland so you can claim the states before the British or French do so coming the other way. After that, Oman and Aden were historically appropriate targets.
- The problem with the Pacific is that I don't like having to launch amphibious invasions to crush rebel islands nor worry about wars from other powers resenting claims. Landing in a safe province and marching overland is safer.
- Picking off highly populated Chinese provinces with teeming unemployed masses can provide all the colonial military manpower you need and some decent revenue, but to get them you need to take the capital and enough else to force them to cede what you want. In 2 wars I took Taiwan, Shanghai, and Suzhou (I think there were about 10 million people in Suzhou, which I fortified and dug in to guard Shanghai from the land side against later Chinese attacks).
- I was attacked in the 1890s by Spain, onetime ally, when I left the homeland unguarded during a Brazilian war. Naturally I shipped troops home, mobilized, and soon enough half of Iberia was green -- it was their own fault.
- Don't waste funds on the navy. You are strong enough to beat weak navies and not strong enough to contest the majors, so use your clippers and steamers for convoys until late game when you can build a few modern warships.
- At least early on, all your Portuguese labor needs to be focused on industry, so build the cheaper colonial troops exclusively. I tended to bolster their stats with extras including artillery. My starting units did develop incredible experience fighting across the world, and the experienced colonial troops had no problem smashing technically advanced Spanish regulars.
- The British will give you expeditionary forces. Use them aggressively or return them -- you don't want to leave them sitting idle, drinking your liquor.
To prevent the growth of the US as an American power and leave things more fluid in the Americas, as well as to have fun to do, I aggressively supported the Confederate War of Independence with funds, tech trades, and expeditionary forces from the very start. Sad to say, they were not particularly grateful.