Available taxis display a bright green light on their roof. Hard to miss. Hailing a taxi is simple. Just wave your hand.
Drivers always use the meter, so you can see the fare as you go. Somewhat confusingly, tarifa 2 is cheaper than tarifa 1, which applies to nights and weekends. There are a few extra charges that might be added: for luggage, late night journeys, and to or from the airport. It's all detailed on a sticker inside the taxi, and you can always ask for receipt.