Check that your taxi driver starts the meter unless you've negotiated a price. If you use car or motorbike taxis have small denomination dong with you as HCMC's taxi drivers frequently carry only small amounts of change. To avoid misunderstandings, it is useful to have your destination address written down. If you can write the address in Vietnamese, even better! To travel one kilometre in Saigon in a taxi costs around USD0.70, and the starting fee for the first kilometre ranges from around VND16,000 depending on the company.
Don't assume that your driver knows where your destination is located. Taxi drivers in Saigon typically grab fares from all over the city but that doesn't mean they are expertly versed in the coordinates of every street, alley or District. After all, Ho Chi Minh City is huge! It pays dividends to write down your destination or at the very least carry a small map or a 3G smart phone with GPS capability. It is advisable to use a taxi from a well-established company to avoid a potential rip-off. These taxis can usually be found parked near four or five star hotels or restaurants.