Books and Magazines were always my sorce growing up.
Some of my earliest memories are of two fish tanks in my parents house. We moved out of that house almost 50 years(omg) ago.
I used to subscribe to FAMA and TFH in the 80's and kept every issue for years. When the internet came around I did get rid of them but I would use them as research all the time. If I saw something in a fish store, I would go home and thumb through years of issues. LOL
I would read like crazy to find out about fish.
Now like others I use the computer too much.
I still buy some books but seldom use them. Heck, I bought several books during our last book group buy and they are still in the wrappers. lol
As far as other knowledge, it was trial and error for me. I am old. Heck my fish room is over 20 years old. I built it before the internet and there were no clubs around for me to get ideas. LOL I just did it.
Take your time and research.
You will not do everything right.
None of us do.