Inscryption

You will unlock Starter Decks after completing Challenge Levels 2, 3, 5, 6, 7, 9 and 11

I advise you use the decks as they are unlocked to complete the next level of challenges. The decks are built with synergy in mind to work with the challenges, cards and sigils that are unlocked along the way. For instance, the Bone Deck is unlocked at the same time the Lammergeier card is unlocked, a card that thrives on using the Bone currency.

You may struggle with some of the decks on your first run as some require complimentary cards, sigils or upgrade events to work optimally, but it is possible to get through even Skull Storm with every deck if you get enough good fortune along the way for a strong deck and useful Backpack items. If you are truly struggling with certain decks, you can always do a lower amount of challenges in a run just to cross the deck off your list of things to do.

Every Kaycee's Mod run will give you these three cards along with two Rabbit Pelts. The Pelts will allow you to pick from a random eight cards on offer from The Trader as your opening event of the game. It is best to choose cards that work well with your starter deck or have Sigils that you can attach to your cards at a Sacrifice event. You want to increase your deck so you don't run out of cards and go into starvation, but you also don't want to bloat your deck to the point you never see some of your best cards turn up in your hand. 

Overall Deck Building Tips:
The biggest tip you can learn about how to play Inscryption (Act I or Kaycee's Mod) is that there is a hidden mechanic in the game known as the "Fair Hand Mechanic." What that refers to is that every card battle you play you will be given four cards to start with in your hand. One of these cards will be a no cost card (typically a Squirrel), one of the cards will be a card you can play by sacrificing that single no cost card, and the other two will be random cards from your deck.

Single sacrifice cards have the below symbol on the top right of the card:

What you want to do is cultivate your deck so that you can have a dependable single sacrifice card that will always be in your hand at the start of every battle. The best example of this is the Mantis God, or "Triple" Deck. If you can dispose of the two Ringworms and never take another Single Sacrifice card, you can play the Mantis God with its Trifurcated Strike Sigil   (triple strike) every hand and once it has an upgraded power level, it will finish each card battle on the first turn.

This will not work for every deck - The Stoat and Bullfrog will never be powerful enough at the start to win you your first Kaycee's Mod run without some major upgrading, nor will the High Cost Deck survive on the Mole card alone, so there are nuances to playing and building each deck. The Geck Deck has no single cost cards so you may see a few of your first hands that need to rely on the Geck before it gets stronger or any helpful Sigils put on it. 

For individual Starter Deck tips and information: I have laid out the best way to play through all 13 runs of Kaycee's Mod, including how and when to use each of the eight decks after unlocking them in the full guide found at Skull Storm  

See the three YouTube links below for an in-depth guide to many of the Starter Decks and two Curious Egg Deck runs:

Inscryption - Start // Finish and other Kaycee's Mod tips (Part 1) 
Inscryption - Start // Finish (Part 2)
Inscryption - Curious Egg Deck Full Guide