Nano tanks are wonderful. A good size is 20 - 30 gallons, with a 29g Biocube a great tank for beginner or expert. Nano's offer a visual perspective that is not often available with a large tank and that is closeness. You can get your eyes within eight inches(or less) of every nook, cranny and growing thing in your tank.
My tank looks like a bit of a dog's breakfast from afar but I designed it to my viewing pleasure which is on a stool with my nose pressed up against the glass. So much life!
Smaller tanks are no more difficult than larger tanks in my opinion. In fact it is easier because maintenance is a breeze. My weekly 10% water change is half a bucket of water. You ask some of the big reefers around here how long it takes to prepare ro/di, mix and hump five buckets in and out of a system and it would be hella of lot longer than my half bucket.
My additives? 1/4 teaspoon of baking soda dissolved in 20ml of water, simple.
Welcome to reefing and Nano!!
Keith