By car:
Porto, like most Portuguese cities, is a nightmare to drive in. Roads vary in conditions - from fully paved to cobbled lanes that can make even the most shortest of distance seem like a go-kart rally. With that said, keep in mind that the touristic part of the city (the Ribeira and Baixa) are a never ending maze of narrow streets, short tempered drivers and snakelike alleys. Better to walk (despite the fact that it's very hilly). Also, drivers seem to have forgotten how to drive (apart from pushing the pedals) - therefore, they make their own rules of the road (however, this generally does not apply to young drivers). Be prepared to lose your patience several times whilst driving.
By Metro:
The Metro operates on a total of five different lines, which are conveniently marked with different letters (A through to E) and by different colours. The metro covers virtually the entire city as well as some neighbouring towns. Trains are clean, efficient and reliable as well as being excellent value for money. Fares are based on destination zones and tickets can be bought at all Metro stations.
By bus:
STCP Porto has many lines and buses, which are modern and comfortable. However, they are not very reliable in terms of timetable, and the bus drivers tend to go on strike from time to time, which can leave you waiting for a bus up to an hour!. However, the lines serve every alley in the city, so you can be sure that wherever you are, there is a bus stop. If you do not have the Andante (see "Metro" above), then the tickets can be purchased on board, for €1.50 or cheaper on most any newspaper seller.
By taxi:
A fast way of getting around the city, although traffic congestions near the city center might be a problem. However, be expected to pay a high price for these services, especially compared to the other public transportations such as bus and subway.
By boat:
There are ferry boats that connect Porto to the neighboring city of Vila Nova de Gaia, although you can easily walk or travel by car, metro or bus to the other side. Also the are numerous tourist boats which travel up the Douro river, where you can get fantastic views of the green landscape the region has to offer.
By helicopter:
Not exactly a public transportation, but its a wonderful way to see the city from above. Near the Douro there is a heliport with a helicopter available for people to use to get to know the city as a whole. Travelling accompanied will make the flight cheaper.
By Funicular dos Guindais:
This is a cable railway system. Use this if you don't wish to walk up the steep streets of Porto. This system connects the Ribeira to the Batalha square, in the city centre, it also has a panoramic view of the River Duoro. As of February 2007, a single trip cost €1. However, if your Andante card (see "Metro" above) has been recently validated (in less then one hour), that you can ride it for free.
By Ascensor da Ribeira:
This panoramic elevator runs from the Largo da Lada, and is visible behind the buildings of the Ribeira, close to the Ponte D. Luís.