After my recent trip to Norway I managed to witness once again the northern lights, I saw it for the first time last year but the show this year was way better, after sharing some photos I got many questions on how to capture them and what is needed.
The first advise I have is to research the location you want to capture the Auroras, use applications like Aurora pro or Aurora forecast to maximize your chances, solar flares can take from 8 minutes to 5 days to reach the earth and short term predictions are usually more accurate then long term ones. Also keep an eye on the cloud coverage of your location. The Aurora can be seen from September to March (depending on location).
When it comes to the camera gear you should you keep in mind that you will need a fast lens, f2.8 or lower is recommended, a sturdy tripod as you will need to do long exposures sometimes up to 30 seconds depending on the strength on the aurora, also you will most likely need to bump the ISO.
A good measuring start if the aurora is just visible but not very green would be a ISO 1000 at F2.8 (or lower) with a 15s exposure, from there I would see what kind of adjustment the image need and would change the settings accordingly.