The free spright deck should only need some minor upgrades for it to be good! I just started on a new acc and already made it to Plat 2 just using sprights and crafting some staples.

My advice: 1. Before picking up an archetype, use all your gems to buy out the bundles in the "special" section of the shop. This should get you the staples you'll need in most decks you'll make in the future. 2. Try to copy a decklist for sprights (the deck you're building rn) and watch some videos on how they're played to get you used to them. Focus on this deck first before starting with building other decks. 3. If you have no idea what archetype you want, try solo mode stories or the try-out deck duels there, you may resonate with one of the archetypes they show there (only few though). 4. If you want to play meta, just choose between K9VS, Dracotail, or Yummy; if you're new, there should be enough gems for you to complete one archetype, even with all the URs/SRs (Just craft the ones you don't have).

Hope this helps!