The Harpa concert hall and old harbour next to it are my favourite places to take photos in the city. I also like poking around the back streets looking for interesting details. However, I'd recommend getting away from the city if you can. Iceland is at it's best well away from Reykjavik, in my opinion.
The sights of the Golden Circle (
https://guidetoiceland.is/best-of-iceland/top-9-detours-on-the-golden-circle) are not far from Reykjavik. I never get bored of visiting Þingvellir and the steaming volcanic hills surrounding Geysir. January should be relatively quiet too. The summer seems to be rammed with coaches these days
Having said that, there are so many lovely places in-between the 'sights' that we enjoy just driving around, stopping for a picnic in random places and hiking for an hour from the side of the road.
The best 'tips' I could give you are to prepare for all weathers, but not stress about what you end up with. Partly because it's such a beautiful country that there's always something to shoot in even the worst light and weather, plus the light tends to change very quickly as systems come through. I'd recommend ISO 400 film as it will cover you for bright winter sun through dull rainy days. Cameras with removable backs are handy for Iceland, so you can swap out colour and B&W. I managed with the Xpan last time, but was just really lucky with getting colour in for the blue sky days and B&W when the weather turned. It was much easier when I took my (long gone, but not forgotten) 503CX. I also spent ages looking for a camera rain cover last time we went, but ended up just getting the missus to hold a brolly—which worked just fine.
Gloves! Take good gloves
...And those studded things that strap onto your boots (
https://www.ebay.co.uk/itm/Snow-Ant...s-Spikes-Crampon-Hiking-Climbing/352863259829). They make clambering about on ice a hell of a lot easier and safer.
Extra camera and light meter batteries, so you can keep a set next to your skin and swap them out if the temperature drops. That said, Iceland doesn't get as cold as most people think, unless you're right in the interior. The ocean air keeps it relatively mild.
No idea about Aurora shooting to be honest...apart from 'use a tripod'! Looks pretty cloudy for this week, so doubt we'll see much anyway.