Being honest with 3.4k gems you can't complete a single deck. My suggestion is to wait until you get around 10k.
Buy 1 return of the red eyes structure deck (500 gems) to beat npc and complete events fast
You can also build a small cyberdark deck, look for it in this page, you can use your tickets to get the monsters and replace spell/traps with whatever you have (don't use your dream tickets)
3.4k gems is VERY enough to build Aromage deck, since half the deck came from Card Trader, while the other half came from a single minibox, and you mostly only going to use the R and N cards from the minibox.
use dream tickets to get staple backrow cards that are usable in any deck, like Cosmic Cyclone and Karma Cut, you can fit them into your Aromage deck as well if you want to