What to Wish For?
(http://wiki.dominionstrategy.com/images/thumb/3/37/Mystic.jpg/373px-Mystic.jpg)
Consider the following situation. You have N Mystic plays and need an extra $1 to win the game. Your deck consists of Coppers and Estates.
1. Suppose you have only N=1 Mystics. What do you name?
You name Copper. Hitting Estate doesn't help you hit $8.
2. Now suppose N=2. What do you name?
Name Estate first. You now also win if the top of the deck is Estate-Copper
3. Now suppose N=3. What do you name?
Name Estate first. If you hit, name Estate again. You now win if the top of the deck is Estate-Estate-Copper.
Of course, if at any point, you know the top card of your deck is a Copper, draw it and win.
General Strategy
If you are digging for a specific card:
1. Spend your first guesses on the most likely "blocking" card. This helps you dig deeper into the deck
2. Spend your last guess on the card you want to find. This maximizes your chances of finding the card that you need.
(http://wiki.dominionstrategy.com/images/6/68/Wish.jpg)