Start keeping all you're cards up to 6 at this point (up to 12 counting ups, once you have some more decks going).
You mainly have the cards for for you're mono darkness right now, so you are actually free to start building whatever you want, since it's basically open field for you.
I personally would start working on one of the many unupped novabows and transfer over to an upped nova/snbow next.
For example:
Start with this:
Up the cards needed for this except for the novas that match this:
And then start building toward that' Upped Bow.
That Upped Bow will be you're final silver farmer, can do some gold from time to time, and can compete in PVP2.
From there, you'll hopefully win enough shards, to build either Voodoo Bravery, Pdials, or Malignant Balls...
You'll have access to Gold/Plat and FGs with those.