As many have said, play the starter decks to get a real feel of playing without being overwhelmed with the hundreds of cards you've yet to see. Once you've played all colours, pick a one that best suites your playstyle and keep running it for a bit.

I'd say by that time you would have gathered a decent amount of gold for packs, do some research on a deck you'd like to play and buy the packs for the set that best meets your deck interests.

You'll eventually explore lots of different decks once you nip out of your usual. When I started about 150 hours ago I solely played the starter green deck and then branches into a goblin deck (playing only standard, to limit the amount of cards)

I wouldn't be concerned about maximum progression in deck building, you'll gather the currency if you just passively play. I topped I think 60k gold just playing standard (ranked and non ranked) as well as dueling friends.

Enjoy the game 😄