Some common mistakes that novices make:

Thinking the game is about who makes the best wine…
It is about running the vineyard. Sometimes your strategy will include making cheap wine, or giving tours, or having lots of visitors.

Training too many workers
Do get an extra one early on, but four is probably enough (or maybe five).

Building Trellis and Irrigation before they are needed
Plant as soon as you can. Only build Trellis and Irrigation if you have to.

Not reacting to the cards
Many novices decide on their strategy without taking into account what cards they have drawn. For example, they might decide to go all out for fulfilling wine orders, without considering whether the cards (i.e. Mama & Papa, orders, vines, and visitors) they have drawn encourage that strategy, or a different one.

Choosing the extra worker in Spring
The extra worker (the one you get if you position your rooster at the bottom of the order ladder) is not as powerful as getting the workers’ bonuses for taking an action early.

Not selling a field
The extra money early on can give you a boost. You probably won’t need all three fields anyway, though you can always buy it back if you do.