I used an immigration service to help me through the process. Alongside that I spent several months learning the language then weeks traveling through PT before making the decision.

You can do the immigration process yourself, but it's a long process with a lot of i's to dot and t's to cross. It was helpful to have experts guiding me through the process. Learning the language also helped a ton. The Portuguese in cities all speak English extremely well, but they really embrace you when they see you putting in some effort to speak Portuguese. I learned with Pimsleur for native pronunciation and Anki frequency vocabulary decks. I had some background with Spanish, so it was easier for me to learn Portuguese than starting from zero.

I also considered Uruguay and Malta but preferred the safety of Portugal and its bigger size.