Having the staple Commons and Rares goes a long way. You hardly need most Epics and Legendaries if you just want to win some games.
So, what are those cards? It’s why I made a list of “Cards for a limited collection”
Once you get to the point you own some staples and good cards, you are pretty much set and can craft some specific cards for a deck you want to play.
And when I say staples, I mean “collection staples”. Cards that you should just keep for your collection. Cards that can stand on their own and/or provide excellent value for your collection. Not necessarily “meta staples”, as is so commonly used.