Ah, ok, got it. For Lisbon, we didn't book any tickets in advance, except that we purchased tickets for the castle online before we left the hotel. There was a long line to purchase tickets at the castle which was a little odd because folks in line could have just used their phones for immediate admission. We did purchase Jeronimos monastery a few days before. Do not wait to buy your tickets until you get there. If you do, you will likely be waiting in three long lines instead of two. Hopefully they have streamlined their ticket and admissions process, but I haven't heard that is the case.
For Porto, if you want to go to the Livraria Lello, bookstore (which looks like Harry Potter bookstore), I'd advise seeing their website and booking something a few days before. For the cathedral, we purchased tickets mid afternoon, no line. The porto stock exchange palace is lovely, check out the website. We purchased tickets at their ticket office right away in the morning for later in the day. I think I heard you can now book online, but check. We did not go to any of the port houses because we had spent three days on the Douro River.
In Braga, don't miss Sanctuary of Bom Jesus do Monte . We got there early in the morning at opening. The church and stairs are lovely. We parked at the bottom and walked both up and down.