Whenever you visit a country where English is not the first, or a popular second language, it is always good manners to learn at least some basic phrases, greetings, essential questions, etc. For many years, I have relied on Berlitz CD Audio courses.
I "rip" the CDs to my Apple Mac as .mp3 files, then copy them to my iPhone. That way, I have the audio classes available to listen to whenever I can. On the long flight over the pond, I use noise cancelling headphones to refresh my learning. I listen through the course while I nap, setting the player to repeat the entire course.
These courses also come with the ubiquitous Berlitz pocket book. The audio courses typically follow the book layout and order.
I accumulated the Berlitz "mini courses" for 12 languages. Before I retired, I traveled all of the world. Trust me, when in Russia, South Korea, Poland, Thailand, or Italy, let alone Spain. The locals always appreciate it when a "foreigner" (YOU) at least makes the effort to be polite and try to speak some of their language. You would be surprised at how this sets the tone for any interchange.
In my experience, if the person you are trying to speak to has ANY English, this attempt will bring it out. Using a "mish-mash" of two or more languages, I usually make myself understood, and without shouting...THAT never works.
But, and truth in advertising here, I MUST refresh my memory before arriving in any of these countries. I am a bright and clever fellow, but I am not a walking library... So, both my Pimsleur Conversational Spanish course, and Portuguese Berlitz audio lessons are out, in preparation for my planned travel to Portugal, and walking from Lisbon in a month or so...at the end of April I think.
As regards the Camino Portuguese specifically, LEARN SPANISH, as you end up in Spain anyway once you reach Tui. But, consider the Berlitz-level effort I mentioned for Portuguese. Consider typing up a laminated, card-sized "cheat sheet" of simple phrases that you can keep in your pocket to refer to rapidly when in a shop or train station, etc.
In Portugal, the most useful phrase I developed, right after "good day - bom dia" was "falla Inglese? (phonetic... "fah-la in-glese") ([do you] speak English?). At least 75 percent of the time, at least in cities and large towns, or among anyone under about 50 years of age, the answer is "Yes, I do...a little."
In one memorable event in 2015 an older woman (I am 63, so I mean a lot older) said "no, but wait a moment..." She whipped out her mobile phone and called her daughter who spoke fluent English. She handed the phone to me so I could speak to the very nice daughter on the phone. The daughter explained to the first lady what I needed. The situation was thus saved.
The reasons are simple: (1) English, Canadian, Australian and US TV programming in Portugal is broadcast in the Original Version (OV) with Portuguese subtitles. One can learn to speak English this way over time; (2) English is emphasized in the Portuguese school system; and (3) MANY Portuguese folks have relatives living in the US or Canada and have visited or gone to university there.
I was saved at the Oriente Train Station late one night in 2015 by a 40-something woman and her teen daughter. Thinking I was well and truly screwed as my late flight arrival caused me to miss my train to Porto and almost miss the last train for the day from Lisbon to Porto, I was speaking aloud to myself while looking at he large train schedule display... "Ok Thomas, NOW what do you do, you are SO screwed!"
Imagine my surprise when, in perfect colloquial English a woman behind me says, "Can we help?" It turned out that she had attended college in the US while living with relatives in Massachusetts. The daughter also spoke fluent English. The daughter happened to be taking the same, last train to Porto. Success! St. James works in really strange ways sometimes. That is my point.
I learned this is not unique to Portugal. TV programming in the Netherlands and the Flemish region of Belgium is broadcast the same way. The results are similar. When I moved to Belgium in 2006, for two years, I was pleasantly surprised after learning some Dutch, that nearly everyone spoke very good English. It is required in the schools there, at the high school level. Still, I considered it proper to learn Dutch to greet older folks, usually the parents of our new friends and coworkers, who did not pick up on learning English.
Conversely, in Spain: (1) TV is dubbed into Spanish; (2) English lessons are available at higher education levels, but not required or emphasized; and (3) far fewer Spaniards have relatives living in English speaking countries. When migrating abroad, many Spanish speaking folks trend towards countries where Spanish is already spoken.
When in Spain, asking "Habla Inglese?" I am typically met with either a polite "no" or a "no, sorry." Sometimes, depending on where you are in Spain, you get a more emphatic "NO, Catalan!, or NO, Gallego!, or NO Euskerra (Basque)!"
I reply with a "Sorry, please pardon my bad Spanish..." ("Lo siento, perdona por favor mi mal español."), then I try to do as well as I can.
Spanish is widely spoken around the world and you will likely use it more in future than Portuguese. Consider that fact when deciding which language to learn.
Being able to speak the local language, even if only a little, breaks the ice. It also signals to the other person that you are a person who respects others, and at least, their language. IMHO, it cannot hurt in any situation.
This leads me to the (tongue in cheek) "Ninth Beautitude." I developed it over three years working as a volunteer at he Pilgrim Office in Santiago de Compostela.
It goes like this... "Blessed are the speakers of English, for they shall be understood."
This is not intended as being chauvinistic or nationalistic. The fact is that English is likely the second language of the Camino, and indeed is increasingly spoken as a second language around the world.
If you have done a Camino, you understand what I am trying to explain here. An increasing number of people have at least some English. There appears to be a direct correlation between youth and adoption of English as a second or third language.
I hope this helps.