Taxis don't have a taximeter, even in big cities. So, discuss (and bargain)
the price before getting in the cap. Pay when getting out.
To give you an idea of the price, the "rate" of a cap is about
50 cents per kilometer, 5 soles minimum. Some cities are big and the price
could go to 25 soles during the day and 40 at night; it is the limit for an
hour and a half trip.
At night, prefer yellow caps that have ID number on the front glass for
security reasons. Check if windows could be opened; in fact, someone I know
has being kidnapped in a taxi with neutralizing gas.
Most taxis have a sticker on the front glass; don't panic if the driver
puts it on when he sees you and takes it out when you leave: in fact, anybody
could be a taxi driver but in some places this is forbidden or restricted
(airports, malls, etc.)...
Personally, I do not recommend to take the taxis model Tico, the are not
at all safe in case of an accident.
In town, there are different kinds of transportation: taxis, collectivos
(they are like taxis but they group the clients all the way long) and minibuses
(micros). Don't look for bus stops or micros in good shape, they don't exist.
Roads have being considerably improved and there are almost no more sewers
without cover... If you need to rent a car, think of air conditioning (even
in winter) because it's safer to keep windows closed (for safety and against
pollution). Except for certain places in the inner land, rent 4x4 is not necessary.