There is alot of experience on here to draw from and also it's not as "hard" as it's made out. I know plenty on aquarium noobies that start and are successful in keeping, the comment previously was just you will need to put abit of money into it. Again it's not as expensive as its made out to be, doesn't cost thousands but it is more expensive than freshwater. Keeping freshwater can be just as difficult dealing with all the chemistry plus fish care but it's all made worth it with happy fish and happy tank, otherwise why would we do it. If your up for saltwater and really want clown fish I would go straight for it rather than spend out twice on two sets of equipment, experience can be invaluable but experience in fresh doesn't mean you know lots about salt, do why not go for it, people on here will help you every step of the way. Providing your honest and accepting of advice and direction it could be a great experience for you and you will end up with your dream 20gal with clowns?
Just a thought. Hope you go for it personally. I went into planted fresh, not knowing anything. I'm a gardener by trade but alot of that experience doesn't interpret to water gardening, so I had and still have alot to learn. The bumps in the road will always help us out in the future and we can share those bumps with others like yourself to help them not avoid the same.