Doing portrait photography and fashion or beauty shots is an opportunity for every photographer to try out different techniques and honing on the creative side of his skills. From this creative point of view its just fantastic as everything goes today.
Booking a model is the first step. Finding someone to sit, stand or lie in front of the camera is not a big issue here in Vietnam. But if you want to be more efficient as to ask just the next good looking girl its commendable to book a model through an agency. They have already a good knowledge of photography and you're getting the look you are after much more easily.
The appearance of your model can change real wildly under different light sources and different light conditions. Try to control the direction of your light to emphasise different moods or show or hide aspects of your subjects character. An effective way to flatter your subject is always shooting in soft light.
Avoid bright sunlight or use it only to get the usual high contrast look with hard edges and shadows. This is certainly not kind to faces. Cloudy sky or shooting in the shadow is the best way to go. Clouds are you're best friend and are like big soft boxes. If you don't want to create your own light with flashes and/or permanent light bring at least an reflector it might come pretty handy.
Here some images of a shooting on location along the railway in Hanoi on a cloudy day in between the narrow line of houses along the Sapa train line. Same model same theme - travelling Lomostyle and one different for a change.