Druid
Choose when to gain mana for later and when to fight for the board now.
What the class does
Druid can gain mana ahead of the normal pace. This lets it play big cards sooner. Some Druid cards also offer a choice of effects. Minions turn that extra mana into attacks and board strength.
The main question is simple: how much can you give up now to make a later turn better?
Make extra mana useful
More mana helps only if you have a good way to spend it. A quiet turn can be worth it if it sets up a strong next play. It is not worth it if your hero dies before that play.
When a card gives you choices, pick the effect you need now. A small effect that saves a minion or your hero may beat one with a bigger number.
Choices to think about
Start with your next useful play and work backward. How much mana does it need? What enemy minions will still be there? What can the enemy do before your next turn?
Setting up a big card does not deal with minions already attacking you. Keep those two jobs separate.
Strengths and weak spots
A well-timed setup can give Druid a large lead in mana or cards. A bad hand may have lots of setup and no reward, or big cards with no time to play them. Change your plan as the board changes.
See Deck Types for general game plans such as aggro, control, and combo.
The linked class guides explain the main rules and older class themes. This wiki supplies the play examples. For exact card details, use current card text and patch notes.