I started with freshwater fish growing up. First stuff like tetra's, mollies, swordtales, angelfish ect. Then from about middle school I kept just about every common south american cichild you could imagine and bred several convict and fire mouth pairs. they were worse than damsels. then I moved to african cichilds breifly but never got into em because I was so much more familiar with south american. had a few gars and pikefish, catfish ect as well. I didn't switch to saltwater until my last few years of college mid 90's. My set up was jus as recommended. a 30g (same size I have now lol), underground filter, crushed coral and a hagen aquaclear 402 (now called model 50) that still worked just fine up 2007 when my tank broke and I stopped using it. that 30g at one point or another had so many fish that should have never been in a 30g its rediculous (all small specimens that look like they'd fit). I'm talking picasso trigger, lunare wrasse, hippo and yellow tang (not all at once). whatever looked good lol. Lava rock. never head of liverock or skimming and neither did any pet stores.
what really drew me to saltwater tanks is the water clarity is just better than freshwater regardless of how bad or good water quality actually is. that and common cheap saltwater fish like royal grammas and clowns would be world class beauties by freshwater standards.