Portugal isn't as peaceful as it was back at launch, with the introduction of those trade bonuses for certain provinces. Since Portugal's goal is to suck as much of the trade of the world as possible to their home node, it's very, very tempting (if not almost necessary) to grab those provinces. Whacking Benin and then Kilwa are your early wartime goals; since the latter has almost certainly blobbed the entire East African coast by the time you get there, Kilwa can be a pretty large and tough foe early on. But since those two won't be as advanced as you, they are a bit of an easier learning curve for warfare than having to learn to do so as a European power vs other European powers. After those two, you start getting entangled with more advanced Asian nations (from Arabia to Indonesia), were some of the more complex facets of EU4 warfare come into play...
That's not really a problem for a new player, in my opinion. Losing a war to Kilwa is about the furthest thing from game-ending. One rather annoying thing about Portugal for a new player is that you start with these explorers, who wreck your mps, and you need to use them right away. The first time I played Portugal I didn't even realize I started with them. It's not as bad as England - you start with I think 1 military point per month is it? Either way, I probably should have though about mentioning starting leaders when recommending nations; I have to assume I'm not the only one who completely overlooked them when new.