By looking up, of course! Technically, you can see the northern lights anywhere in Iceland, as long as the sky is clear enough. There are great places in Reykjavík that you can view the aurora from, but as you might expect, it’s ideal to go out into the countryside, as far away from the city lights as possible.
You really want clear skies when hunting for the northern lights in Iceland. Because the northern lights depend on weather conditions, solar activity, and the earth’s atmosphere, seeing them isn’t always a given. You might want to read up on aurora forecasts here before you head out, which can be accessed at Icelandic Met Office’s official website.
Many tour operators offer special northern lights tours, where a bus will take you outside the city in search of this natural phenomenon. Your guide will be acquainted with the best spots and will have consulted the forecast beforehand, so this is a good bet for travellers who just want to show up with a camera and hope for the best. The northern lights being a natural phenomenon, the usual caveats apply, though many tour operators will offer another tour on the house if the “green lady” doesn’t make an appearance.