Most tropical fresh water fish you can get in most stores have similar care requirements, it’s mainly the size of the tank that is the main differential. A few fish like the water a bit hotter and a few have special requirements like food (e.g. puffer fish). How big is your wallet?
If you really like clown fish then there is nothing stopping you buying a salt water tank first. They don’t need to be kept with corals and tend to be pretty easy as far as salt water fish go. Outside of changing salt water the care requirements are not that different to a tropical tank if you only keep fish. The secondary problem with saltwater is that it inevitably escalates past just fish and that's where the complexity and the costs escalate very quickly.
Do the research if your happy with the commitment then go for it. But do your research otherwise it will end in tears, there is loads of information on the web.