Here are a couple of general rules:
1. Pig Breeding is a vital source of income, and should be activated asap.
2. First turn, you want to lead with a farm extension like 99% of the time. Even if you're going for round1 greengrocer, you still need that extra delivery. Also it gives a really appreciated boost in card quality (as it lets you keep more cards).
3. Always try to get the 2VP bonus for completing the first 3 craft buildings. Especially in a 2p game, as each is a 4point swing.
4. The greengrocer is the easiest way to activate your pig breeding, as you get a pig + one more before your next breeding phase.
5. Helpers and fields offer more value the earlier you play them.