Ive played quite a bit of portugal, here are some notes-
-You get 200 free admin from a mission to take and core tangiers. I usually take the papal relations mission first then that. Rush mil tech 4 and grab a commandant or army reformer and morocco cant beat you while still at tech 3, even if they get a stupid alliance block set up with tlemcen. After the first war Take tangiers, but also take mellila and fez and release fez as a vassal. Fez will be a useful vassal to eat up most north africa land you want to take until later game. after this take the mission to expand the buffer zone. War again and take gharb and some stuff inland for fez. DONT TAKE OTHER COASTAL PROVINCES FROM MOROCCO YET- you get an event that gives you free claims on the entire moroccan coastline later.
-Ideas push for exploration and expansion ideas fast. Castile almost always takes these as well and will get one more colonist than you total so you want to beat him to the good stuff, unless you plan on just wiping him out. Some people will 'meh' at expansion, and while its not as strong as it once was for portugal its a great idea set. Grab colonies off the coast of Africa and trade centers/estuaries- be sure to grab cayor and benin at some point, add all land here to trade companies. You now control Ivory coast trade by far.
-in the new world you have some minor native tags in brazil now so getting the 5 provinces you need for a colonial nation is EZ. Focus on brazil and carribean first in the new world, then conquer 5 provinces in mexico and peru to claim those Colonial nations. Columbia and la plata are nice as well but you can skip them if you really dont care, same with louisiana and california. Ignore the american east coast entirely, the trade doesnt even feed to sevilla so its wasted effort.
-Take south africa and then use the same strategy in ivory coast for zanzibar. At some point you will get gao for free. after you do have some light ships protect trade in the gulf of aden, you will get an event giving you permanent 25 trade power there once you do. at this point you can start colonizing the spice islands and SE asia area. You will now no longer have to worry about money for the rest of the game.
-Build manufactories EVERYWHERE. Do it as soon as you can afford to. The amount of money they produce is stupid, you will be printing ducats. By 1600 you can easily have the highest income in the world off trade bar none, possibly sooner.
-In europe do as you please. I usually play mostly peaceful and only mess with other colonizers that go protty and take land in my colonial areas. Castile/spain will actually be very weak later on since you are taking all the income from the sevilla node. Mix high mercantalism, buildings, and ideas, you will have no contest controlling the node even if they have sevilla. I use them as a meat shield early then decide their fate later in the game depending on how much they are annoying me. After 1650 or so i screw up the ottos, usually with a strong alliance block. Its just fun to do.
-Develop your home provinces as much as you can afford to, especially manpower- you will need it. Manpower can run out fast as portugal, since you dont have alot to start with and eventually have more money than you can spend to build armies/navies. You also do alot of fighting in high attrition areas so be mindful of it. My old strategy before CoC was to spam merc infantry armies with Regulars for cav and art, but thats less viable now due to army professionalism. I usually take quality and offensive for military ideas, and try to get high discipline/professionalism so you take less damage in battle. Just watch your attrition carefully and try to keep that manpower pool up as much as possible.
-Pop your golden age early, you will want to rush filling out exploration ideas, so you will fall a bit behind in diplo tech early. It will help you catch back up, and golden ages scale better if popped early as opposed to late in general.
-Pump your estates for monarch points every 20 years, and early game remember if you arent loaning you arent trying. This is just general advice for any nation but still should always be included.
Any questions let me know, id be happy to be more specific if you would like.