Money is a crucial resource in 7 Wonders Duel. Take gold cards highly as they give you the financial freedom to take the cards you want later in the game. Don't forget that when you discard a card for coins, you get an extra coin per gold card, which makes them even more valuable.

Look to cut your opponent off from a certain type of resource if they aren't set up well to generate money consistently. Even if you took two wood in Age I for example, taking the double wood card in Age II can be very strong as each excess wood your opponent needs costs 6. This will cut them off from many strong plays.

Use the knowledge of how much money your opponent has to your advantage. It might be ok to reveal a card that is very good for them if they don't have enough money to pay for it. Note that if you take a resource card to reveal it, you might even increase the price for your opponent.

When possible, make your opponent reveal face-down cards to you rather than you revealing cards to them. This way you will have first shot at the best cards. In Age I, the first player is advantaged in this regard.

It is very common for games to end in military or scientific victory (Approx. 20% of games end it military supremacy, another 20% scientific supremacy according to BGA Data). The crux of the game's strategy is whether to commit to one of these paths to victory, or to take just enough military/science so your opponent can't win this way while maintaining a victory point advantage.

Wonders that provide you an extra play are extremely powerful when used at the right moment. A well-timed double play can be the key to snagging a military or science victory in Age III with a card that your opponent would otherwise never reveal to you. Likewise, it may save you from a mid-game victory from your opponent!

Make sure you are aware of what science symbols are available in each age. There are 4 unique symbols in Age I, and the same 4 appear in Age II. None of these symbols appear in age III, however, which has 2 other unique symbols. The Law scientific token counts as an additional symbol, so note at the start of the game if this is available as it greatly increasing the chances of the game ending with a scientific victory. Be aware this token can be found with The Great Library wonder, too, even if it is not revealed at game start. If you enter Age III with only 2 science symbols, you will be unable to win a scientific victory.

The Mausoleum is a strong wonder due to its versatility. If your opponent has it, be mindful of what is in the discard as they may surprise you with a mid-game science or military victory.

Duel is a zero-sum game. Getting a high numerical score means nothing compared to beating your opponent. Making a 5 VP play that leaves your opponent with their best play being worth 3 VP (+2 VP to you) is a better exchange than making a 6 VP play that gives your opponent a 10 VP play (-4 VP for you). Even though the first play scored you fewer points, it brought you closer to actually winning the game.