Praia de Moledo is certainly the best wave spot in Northern Portugal. It is a the border with Spain, there is a strong venturi effect for North winds, the beach is beautiful, waves are very clean and accessible for intermediate riders.
Mindelo is the safest and easiest wave spot in Northern Portugal, with nice waves on the beach break.
Praia de Leça is just above the Port of Porto, it can be intimidating as there is the huge pier protecting the Port downwind of the spot: there is no backup there, just don't end up in the Pier downwind. But the waves on the beach are very nice, you will probably have to navigate through some surfers as well as the space is limited.
Praia sul da Cova is a nice wave spots in Central Portugal. Nice small to medium waves will offer you good sessions with a surfboard but beware of the beach crowd.
Praia da Costa de Lavos is one of the best wave spots in Portugal and probably the best in Central Portugal. Very long clean waves will offer you magical sessions with a surfboard in an uncrowded setting. The quality of the waves offer very good potential for big air as well.
Praia do Norte in Nazaré. Obviously unless you are a professional rider you don't want to ride nearby the Fort where you will need backup and security. But north of the beach can be nice to catch some smaller waves (relatively to the massive ones).
Praia do Baleal (Sul) nearby Peniche is a difficult spot, the waves can be very big, and they are often times very close together, and there are areas which are messy and have current.
Easier spots are Areia branca and Foz do Lizandro.
World famous with surfers, Supertubos nearby Peniche is exclusive, recommended for professional riders.
Praia do Guincho is well-known as a kitesurf spot in Portugal. Very difficult spot: the wind is always stronger in Guincho compared to other nearby spots, because of the cliffs along the coast and the venturi effect. Do no mistake, riding there can be tricky: there are rocks in the middle of the spot and rocks downwind. Make sure you know what you're doing.
Praia Nova Vaga and Praia Bela Vista are two spots on the Costa da Caparica, these are very nice for big air and for waves but can be frustrating for wave riding, especially in summer as there are many swimmers and the beach lifeguards whistle at you to move out. The wind usually lifts really well here.
Fonte da Telha is also on the Costa da Caparica, but less accessible and parking there can be a nightmare especially in the summer. The wind is usually stronger than in Praia Nova Vaga and Praia Bela Vista.
In general the Costa Vincenta does not have kite spots.
Praia dos Aivados and all big sand beaches further down south.
One exception is Praia da Bordeira which is a beautiful surfer spot, and is very nice for kitesurfing as well with the north winds, it is common that the wind is much less than what the forecast indicates, so make the trip only if the forecast is strong.
The main wave spots in the Algarve are Praia de Faro and Praia de Cabana. Note that there are no waves in Faro and in the Algarve with north winds.