The city centre is small enough to cover on foot. Jinnah Road is the main thoroughfare and runs past the Tourist Information office, the bazaars and most of the British-era cantonment buildings; the Archaeological Museum and the bigger hotels are all within walking distance. For longer trips around town the standard option is the auto-rickshaw — cheap, ubiquitous, and increasingly being replaced by cleaner CNG four-strokes. Negotiate the fare before you get in.
For day trips to Hanna Lake, Hazarganji-Chiltan, Urak and Pishin, hire a taxi for the half-day; most hotels can arrange one. From the airport, ignore the touts and arrange a hotel pickup or a metered taxi at the desk. If you are a foreign traveller you will likely have a police escort assigned to you on arrival, who will accompany you on any movement around the city or out of it.