Check the Edges
Many of the treasures you are searching for will be partially off-screen. Thoroughly check the edges of each room, especially on the left side. Check the windows too, as treasures are often hidden there.
Wordplay
Your list will have some words that could be taken multiple ways. For example, if the list says dollar, it could be a sand dollar or it could be cash. Every wrong click will cost you air, your most precious resource to winning this game.
Air Issues
Air, also known as your timer, is a huge issue. Go through the lower parts of the level quickly at first so that you can get to the end without running out of air. If you need to go back later, you can.
Every wrong answer costs you 10 seconds of air. While it may not seem like much, it can add up quickly.
Finally, use hints sparingly. Each hint you receive will cost you two minutes of air, something you cannot afford.