By taxi
A good way to move around to not-so-close places. They are not very expensive and drivers are mostly friendly, although small cheats are not uncommon. To avoid it, after getting into a taxi, check if the taximeter has been started . If not, ask the taxi driver to do so.
By Streetcar (Tramway)
There are a couple tourist routes with early XX century streetcars.
By bus
Buses are a cheap and nice way to get around by day, although by night they become more scarce. The fare is payed either with tickets, which can be bought in most bus stops, or in cash to the driver, or conductor by passing by turnstile. Keep an eye out for pickpockets when the bus is crowded. Many people still get wet from the sea into the bus, so have a good look if your seat is dry before you sit.
By bike
Bicycles are by far the best way to move around the town, but unfortunately there are not many places where you can rent one but plenty where you can buy. It's not allowed to ride on most of the beaches during the day. There are some "ciclovias" bikelanes, specially a well-signed one in front of the beach. Better safe than sorry: buy a padlock as well.