Hi Siom: - again, apologies for the delay in response. The route is well marked where it is (infrequently) necessary, but in general you just follow the coastal path all the way from A Guarda to Baiona. Baiona to Vigo and on to Cesantes has more urban stretches and the markers are plentiful. There is a pavement plaque at the harbour in A Guarda, marking the start of the "Caminho Portugues A Costa". It was the recommendation of a friend from the
Camino Frances who I met in Tui and who persuaded me it was worthwhile. I caught a bus from Tui back to A Guarda, walked the first day to Baiona (fantastic coastal scenery, waterfront monasteries, small villages); the next day to Vigo, where I stayed with my friend and the third day to Cesantes. You could do it in two days, but then you would also have a long leg back inland to Pontevedra.