Good advise, and defo smart not to jump in buying a lot of cards from the start. First see what you need and what a card does, better even to maybe rent some cards to try them first. That can be done for less than a cent a day in some cases. When I started, they still gave beta packs per daily quest, so I first collected a lot of cards before spending money on the game (starterdeck and a few packs before it went live excluded lol)

I honestly thought when I started playing that I should sell all my cards except for the death splinter as I only won playing death. Turned out, that I just accidentally selected a good order of monsters with the death splinter that worked, but with the other splinters I put ranged up front etc :) lol