There are many ways to play Crayne but one of the simplist and most effective is making the maximum use of the discard discount system. Having a discard pile full of faction cards during a high revenue round is the most effective way to fill up your deck with valuable cards.
This is why I treat Crayne, particularly the early rounds, a bit like farming. First I start by sowing the seed; while my discard pile is empty I'm busy playing as many faction cards as I can (sowing). Then, when my deck is almost out, I play a round with high revenue and purchase as many cards as I can (harvesting). This allows you to make optimal use of your faction discounts.
In this way I like to think of rounds a bit like seasons. Plant the faction cards into your discard pile using the early seasons (rounds) and harvest new cards in the later season before a shuffle.
Here is how it works in its most basic sense. At the start of the game you will have 12 cards. On your first turn you will always pick up another card, even if that card is only a mercenary. From this point onwards you will have 13+ cards in your deck. This means you will always (unless you cycle cards in some way) have at least two rounds between each shuffle. The first of these two rounds should be spent playing faction cards (sowing), and the second round spent playing trade carts (harvesting). Repeat this cycle until you have 18+ cards.
Once you have 18+ cards you will (generally) have three rounds between shuffles. This means you should spend the first two rounds sowing by playing faction cards (incidentally this is when I start to think more about combinations/synergies), and the third round is spent harvesting, usually aiming to buy the big, expensive cards.
This can continue from 4 rounds per shuffle and beyond, though do remember, you aren't trying to get the biggest deck. You should be aiming to get the cards that synergise best with your chosen stratgy. It is more than ok to waste some of that revenue. Also, at some point in the early/mid game you should be starting to cull cards from your deck. This will also effect how many rounds you get between each shuffle so be careful.
There it is! Simply sowing the seed and harvesting the cards. Farming.