Hi Sandy! Thank you for joining and also for jumping in and making a post!
My husband and I went several years ago. The best time to see the Northern Lights is usually spring but having said that, we went in spring and did not see any! We booked several trips through Viator and all were seamless.
https://www.viator.com/Iceland/d55-ttd
There is so much to do. #1 I would recommend Ice Cleats, you can buy these on Amazon. They are a must if you don’t want to slip and fall. You just snap them onto the bottom of your shoes.
Also, layer up, it really wasn’t much colder there than it was in NOVA in the winter, but lots of layers will keep you warm. If you are staying in Reykjavik, walking the downtown area and trying some fish soup are a must. We wanted to do a helicopter tour , where you can see everything in one day. If funds allow, that would be a must. Unfortuantely when we went it was too windy. Otherwise, you want to try to snag a view of the northern lights ( usually a bus tour), Try to visit the Blue Lagoon, Golden Circle Day trip was fun, Try to see some Glaciers, water falls, a black sand beach and Geysirs. Also we did the Snaefellsnes tour, so much fun! Plan on getting lots of exercise, take some good warm boots you can walk in. Carry extra socks in your backpack in case your feet get wet!