The best way to explore the beautiful region of Serra da Estrela is without doubt by car. You can easily visit beautiful several beautiful towns near the mountain.
If you come from Lisbon, take the A1, the IP6 and the IP2. If you come from Porto, the better trajectory is A1, IP5.
Here are some distances from Manteigas the place I stayed, to beautiful places I had visited:
Guarda – 42 km
Belmonte – 26 km
Seia – 36 km
Sortelha – 50 km
Folgosinho – 47 km
Sabugueiro – 29 km
Arriving in Serra da Estrela by car is a good option, as public transportation doesn’t seem to be that efficient there, … Also, if you have a car, moving around will be easier as the mountain is huge and has so many beautiful places to discover. Before you go to Serra da Estrela, check with Tourism Office about the snow and road conditions, as sometimes roads are closed due to ice.