Dominion is a game about building a better deck than everyone else at the table. You all begin with the same humble ten cards, seven Coppers and three Estates, and from there the game is a race to reshape that deck into an efficient machine. Because you draw only five cards each turn, every card you add either helps or dilutes what you can do. The best players think of their deck as a whole rather than as a set of individual purchases.
The early game is usually about money. Silver and Gold raise your buying power so that you can reach the expensive cards that matter, and a common opening is to add a couple of Silvers before committing to a strategy. As soon as you can reliably generate six or more coins, Provinces become the prize, since they are worth six victory points each and are the most common trigger for ending the game.
Action cards are where Dominion gets its depth. Cards that give extra actions let you chain multiple effects in a single turn, cards that draw more cards keep your hand full, and cards that grant extra buys let you gain several cards at once. When these effects combine, a well-tuned deck can play through most of itself every turn. Building toward such an engine is often stronger than simply buying treasure, but only if the Kingdom cards on offer support it.
Trashing is the quiet skill that separates good decks from bloated ones. Removing your starting Coppers and Estates thins your deck so your powerful cards appear more frequently. A smaller deck is a faster deck, and speed wins races. Cards that let you trash for benefit are often worth prioritizing.
Finally, keep one eye on how the game ends. It stops when the Province pile empties or when any three supply piles run dry. A sharp player can time purchases to empty that third pile while they are ahead, denying opponents the turns they needed to catch up. Knowing when to switch from building to scoring is the heart of Dominion.