How to Count Cards in Dominion by Adib Khoury

This guest article was written by Adib Khoury. He's a board game collector and a senior game-design student at UT Dallas.

Basics
The basic point of this strategy is know how much buying strength you deck has. This is done by keeping track of three values. This technique will take some practice to master, but it is very rewarding if done correctly. (rmcantin)

Card counting helps you choose between action cards to play. It also helps you know when to start discarding copper coins and what cards are needed to balance out your deck.

Buying Power
To count your buying power, simply keep track of the total value of value of coins in your deck.

Do not count the coin value on action cards unless you are confident that they can be played. Action cards are not guaranteed to be played, especially if you draw more than one in a turn. (rmcantin)

Whenever you draw coins from the deck, subtract their value from the total buying power to know how much.

Your goal for the first part of the game is to have a buying power of 6 for each 5 cards in your deck.

Action Power
Action power keeps track of your action count in your deck. Every action counts as a -1. Action cards that give +1 actions count as 0. Action cards that give you +2 actions, like Village and Festival, count as +1 for determining the action power. (rmcantin)

The goal is to keep the number as close to positive as possible, otherwise you will not be able to play your action cards and they will start to slow down your deck.

If your Action power is positive, you should be able to safely include coins on action cards toward the buying power.

Deck Size
Keep track of your total deck size and your current deck size. By keeping track of these two values you can compare them your buying or action power to predict how much gold you will receive next turn.

You don’t have to count buying and action power at the same time. For new players, this could easily become overwhelming, so take it slow. Don’t worry about messing up, because that is part of the game.


References
rmcantin: http://boardgamegeek.com/thread/411962/advanced-techniques-card-counting