In my opinion a nano reef tank is one of the hardest things you can do. Corals need very specific, very stable conditions and doing that in a small body of water is hard as parameters shift faster the less water there is.
It can be done but needs a lot of work. As above stick to soft corals and not lps/sps corals as they are a lot harder to keep. To add to the list Greenstar polpys, leather corals and xenia are all fairly robust and spread nicely.
I also don't think 8G is suitable for clown fish. I also don't think clown fish are really reef safe anyway. I lost a lot of corals to clownfish hosting behaviour.
Have you got an equipment/shopping list ready yet? What stage are you at knowledge wise?
The main things to consider with marine is that everything is much more sensitive to water parameters then even the most delicate freshwater critters. Also the majority of marine fish are super territorial and aggresive. This means that you normally need to stock them a lot lighter then freshwater setups and many fish, even small ones need a lot of territory space.
Whatever fish you like do a LOT of research on them first. Dragon's like mandarins for example are a bit of a trap. They are tiny, unagressive, very pretty fish and look perfect for even very small aquariums. However their diet is mostly copepods so they will normally starve to death if you don't have a very large tank with many KG's of mature lovelock and a good pod population to support them.
Without knowing where you are at right now I'm not sure what advice would be best. Happy to help guide as much as I can though.