You can keep moving portals without actually changing the location of the portal you keep 'peeking' from.
Place a portal (For example, the blue portal) on a wall in an area that you can just walk through that portal. Come out to the other side and shoot that side's portal (the orange portal) to a distant location. Move quickly back to the other side (blue side) while the portal (orange) is traveling to hit the surface. Now, the blue side shows the new location. Most people prefer this method over the Portal Standing method, because it is easier to execute.