Both the Camino Francés and the Camino Portugués in all their variants are well-marked.
So, all you have to do is follow the arrows. Or the shells. Or the signs.
The yellow arrow.
The most common symbol is the yellow arrow.
You'll often find these in cities on lampposts and electrical boxes. Alternatively, they can be on the ground or on walls. In some cities, like Vigo, you'll find arrows partially in shop windows.
Outside of inhabited areas, dedicated signposts are often set up. If those aren't available, they can be larger stones or fences, walls of ruins, or sometimes even trees.
In the past, the arrows were often spray-painted yellow, but these are increasingly being replaced by more durable and better-visible arrows.
Especially in Galicia, where all the Camino routes lead, the arrows are now very often on beautiful stone pillars.
The scallop shell as a trail marker.
The scallop shell is also a trail marker, but it's a bit more complicated than the arrow.
For one, it can be any color, and secondly, I can never remember which direction it points. So, should I walk towards the open or closed side of the shell?
(It's towards the open side).
Fortunately, the shell often appears in combination with an arrow, but if not, this knowledge is important 🙂
Signposts.
In some places, mainly along the Camino Francés, the trail marker can also be in the form of signposts. Fortunately, this is rather rare.
False Friends: blue, green, and black arrows.
Caution: not all arrows are intended for pilgrims. Or not for all pilgrims.
A black arrow on a yellow background has a different meaning and can be ignored by pilgrims.
Blue arrows are intended for pilgrims traveling to Fatima. If you're on the Camino de Santiago, you can ignore the blue arrows.
Green arrows mark alternative routes that are not official.
For example, on the Camino Portugués, there's an option to walk from Baiona to Vigo along the coast.
If the trail marker is missing...
What to do if there are no trail markers at all? No arrow, no shell, no sign, nothing?
Firstly, usually there's something there. It's just not where you're looking. For example, at roundabouts, the arrows are often on the following street. Also, at forks in the road in nature, the next arrow might be on a tree 20 meters further ahead.
If you still can't find anything, you can consult my pilgrimage guide to see where to go. It's so detailed that you can immediately see where you are and where to continue.
If you don't have one, you can access various apps that include maps. These include Camino Ninja, Camino Tools, or Buen Camino.