I am having trouble picking the right ending when turning a Noun into Plural form.

Either I am misunderstanding the spelling rules, or I don't have the complete set... or there are lots of exceptions.

Has any non-Russian learner cracked it...?
Or could a Russian person explain it to me?

Maybe we can make some kind of permanent thread or lesson about this; I can't be the only person having a hard time with it...




площадь - площады
площадь - площади