Vientiane is pretty easy to move around in although be warned that most maps are not very accurate and rarely to scale. Traffic here is not as thunderous as other Southeast Asian cities and the local people will help where they can but most do not speak much English so bring a translation guide book if seeking directions. Also be warned if attempting to use a pedestrian crossing as drivers do not pay them any attention and generally will not stop.
Taxis are readily available with fares being negotiated as you go, most are also happy to be rented for the day at a cost of around $30USD. Tuk-tuks and song-teows also navigate the city streets. Tuk-tuk drivers usually charge the most and will not barter on a fare.
White mini-buses and the old blue and white ones take passengers out of the city to places such as Buddha Park and Friendship Bridge, the one signposted to the airport does not actually go quite that far and you will need to walk a bit at the other end. Vientiane lends itself very well to navigation on bikes which can be hired by the day by leaving a small deposit. Cars can also be hired through international companies such as Europcar as long as you are happy to take a chance on the local erratic driving.