In Typinator — my goto abbreviation expander — you can decide if an abbreviation is considered only when it’s a word or immediately when you have typed the letters. You an also choose wether case is considered or so on. So many possibilities !
I’m writing mainly in French, so I couldn’t give insightful tips about english abbreviations. But I can say that I already had in my brain quite a few abbreviations of common words coming from handwriting/note taking and I just transferred them into Typinator. With time, the repertoire just grew and grew.
Like with starting with Obsidian, I’d advise that you start with a few natural abbreviations. Then, with time and practice, you’ll progressively come to new ideas and you’ll memorise along the way. For this an “easy” tool like Typinator comes handy, because you’d never do the setup involved if it’s too convoluted.
My two cents.
Olivier :-{)