Luggage and bags:
Day sac for carrying camera guide book, water etc, Travel light, the streets in Porto can be quite steep, with uneven paving
Clothing/Shoes/Weather Gear: Flat comfortable shoes- Porto has some steep streets, and some of the pavements are uneven!
Come prepared for all weathers- wear layers, and bring a waterproof (just in case)
Toiletries and Medical Supplies: Porto has plenty of pharmacies. Carry all essential medications.
Sunscreen- I forgot/didn't think it would be that hot in March, and suffered a burnt nose!
Photo Equipment: Plenty to photograph! Come prepared!! Plenty of places to buy film/have films developed, buy batteries, memory cards etc.
Miscellaneous: Binoculars for viewing Porto
Phrase book - try a few basic phrases, always appreciated!
Bubble wrap for transporting pottery/ bottles of port home safely.
Toiletries and Medical Supplies:
The beaches of Porto town and all its region are very rich in iodine, much more than in the south beaches as Lisbon or Algarve.
This way, you will be skinned much more quickly then you think (specially if the sun is cloudy !). So, be provident and pack your favourite sunny body products just for the possibility of any excess of sun exposition.
Luggage and bags:
Travel light if you intend to travel in the public transports. Still the best is to take the special or a cab. Otherwise transports get crowdy and you'll need to bring clothes unless you cope with the rain.
Clothing/Shoes/Weather Gear: Most of the turists that I see around during winter mange to hold to the essentials and go around with the raining kit: umbrella and coat or water-proof coat with hat.
You might find it a bit cold around here but judging from what one sees around the north of Europe that really depends on how much you can cope with the temperatures.
It's hard to snow at most of continental Portugal. And it rarely snows on low lands. So you shouldn't expect nothing but rain and low winds in Porto.
The temperatures go around 10ºC medium temperature. But I wouldn't find it unusual to get temperatures around 15 or even 20ºC on some days on a good year.
Toiletries and Medical Supplies: Flu or any other seasonal diseases. A flu jab is allwyas advisable, even on your own country... The Hospitals are, as in many countries, pretty full that time of year, so it might take a little while to be treated.
Photo Equipment: Good warm light is still available on some days but the skies become somewhat clouded most of the time. So you ought to expect to take more photos indoors, perhaps with flash where allowed.
Camping/Beach/Outdoor Gear: If you intend to go outdoors in the sense of hiking or any other kind of outdoors sports you should prepare yourself. The rain here is heavy and gets into the bones when it hits you ;) It might dry off imediately afterwards and it mught not. So, good water-proof gear should be considered and some thick clothes depending on your abillity to cope with the temperatures.
As for the beach you might expect some good walks on a weekend afternoon but I wouldn't think of going in the water. The water temperatures are low, the beaches are unsurveilled and the waves are usually pushy.
Luggage and bags:
Good tough wheels, if you are considering walking around the city centre with one. The pavement is generally good but the walks aren't that much.
Clothing/Shoes/Weather Gear: Light clothes, its usually real hot around here. You might want something warmer for the nights or something wind-proof if you intend to go near the ocean or for those windy days.
Toiletries and Medical Supplies: You'll find most of it around here easilly. Some medical suppllies may change name here but you can still find what you need.
Photo Equipment: Loads of light, nothing special needed. Perhaps a skylight lense will do well on sky photography but generally any camera will do the trick.
Camping/Beach/Outdoor Gear: Light gear. Be prepared for loads of nasty paths if you go hiking!
Clothing/Shoes/Weather Gear: Be sure to pack to pack some good shoes. All things to see are within walking distance but the roads are not very even. They go up and down and the medieval stones are still there....