Hearthpwn

You can see the decks on the official site for the game, there are even decks for starters marked as #starter:

https://www.playgwent.com/en/decks

As for assistance, I think you can look up on youtube, there are quite a few people doing analysis of decks, even though it may not be for complete beginners. I've been playing a lot in beta, and after release I quit for some time, but now I'm returning a bit to it, so for me, the same, it's like a new game.

A very general tip: really read the card text, because often the mistakes come from the wrong placement (even though they've apparently added some helper for that, it ask you if you put on a wrong row, but it won't help if a card has an effect for both rows).

In the last expansion they've added cards similar to quests in HS, and it's quite fun.