Thank you. I started the hobby back in the Jurassic, when my dad got tired of losing me in the feed/hardware store, which had a tiny 3 gallon with aeneas catfish which occupied my attention so I didn't want to leave. Bless him, my next birthday, he got me a 5 gallon Metaframe, sand, catfish, danios, a ceramic grass hut, some weed, and bubbler, and told me it was my responsibility, which I took seriously. I cared for that tank and by the time I was in my teens, I had that tank and a 10, and angelfish; in college, I had a 20, and a 10, and another 10, with a 'rescue' piranha, angels and guppies, not to mention the rescue salamander. I went marine once on my own, and finally went to a 100 with a 50 gallon sump back in the 80's, got out of the hobby on a crosscountry move---and moved in down the street from a reef store.
Ah, me. I started with a 52 which is now freshwater, and now a 102 quarter cylinder damsel reef, which is kind of my dream tank, cranky as it has been. Plus a 5000 gallon koi pond we dug. Back in the 80's we struggled to keep shrooms and palys alive; now we have stony hammer growing like a weed and we're keeping the fussier sps fairly well.
The hobby is constantly changing. When I started the 52, the wisdom was no canopy on a reef; now my 102 has one, because lighting has changed: LED, and no troubles. So whatever you learn, be open to learning a better way, but old knowledge sometimes serves...there are situations where an old Vortec diatom filter could save one's bacon, but the days of crushed coral, where we used to use them fairly regularly, are gone. I cycled my first 100 g marine tank with nothing but dry rock and a gallon of fish store water tossed into the system. Took 12 weeks, but it became pretty. And after 84 days of no fish, the fish store water is no huge threat---so it worked; most methods can get you there, given sufficient patience. Back in the day we feared bristle worms, now consider them essential. We didn't quarantine...that changed. We installed things like sea apples. Really bad idea, tank-nuking mess. So when we say 'bad idea,' some of us have some real vivid memories of why.

The best innovation outside of cycled tanks and live rock is RC itself---the ability to tap into the collective experience of hundreds of thousands of people. Priceless. I ask my own questions, and back comes an answer in hours. We never had that Back in the Day.