Hi Sue,
The route out of Santiago to Muxia and to Finisterre follow the same path for a couple of days. As you arrive at the Cathedral in Santiago down the steps into the Praza do Obradoiro, the big square in front of the west face of the Cathedral, instead of turning left to go into the Cathedral, go straight on from the bottom of the steps and follow the street ahead of you. There are signs on the route, but maybe getting a street plan at the Information Centre in Santiago would be useful.
Once out of Santiago you head for Negreira and Olveiroa, then a kilometre or two after the small village of Hospital the routes to Finisterre and Muxia split up at a big roundabout. There is a sign at the roundabout showing the split, left for Finisterre and straight on for Muxia on a road to Dumbria, then on to Muxia.
In the village of Hospital there is an information centre with a map on the outside wall showing the details of the routes to Finisterre and Muxia from there.
Buen Camino,
Mike
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