Walking around Vietnam is an exciting new adventure, however initially you will feel intimidated by the chaos. It is important that you cross the road slowly and NEVER RUN. The traffic will weave around you if it knows where you are going, so be predictable. Watch how the locals do it and at first cross with them, you will get the hang of it if you just relax.
For the first-time pedestrian, crossing the road is a daunting experience, but, amid all the apparent chaos, the "system" works. The trick is to just walk when you can, and let the torrent of bikes flow around you. Don't look left, don't look right. Just walk.