If you have an iPhone / iPad, take a look at TrailSmart (it's listed in the forum's Resources area). My favorite feature in the app addresses exactly your sort of situation. You can toggle the routes / sections to go either way. Then you can just follow the handy yellow arrow inside the app. Any time you aren't sure about which way to go, pull your phone out, hold it in front of you, look up and smile at the satellites (optionally waving to the friendly folks at the NSA), orient yourself so you are facing the direction of the arrow, put your phone away (until you need to check you position again), and start walking. No data connection required. The arrow will even point you back to the trail when you are off-route.
The app is free and there is no advertising / gimmicks. The only thing with a price tag is the optional offline maps but those aren't really needed for your purposes (Google's online maps are supported free too). Disclosure: I'm the developer. I don't have the trail to Fatima in the app yet, but the Portugués is covered all the way to/from Lisbon (though the coverage of albergues / attractions is still sort of sketchy south of Porto - working on that now!). Hope that helps.