Early in the game, you’ll benefit from the invaluable assistance of crew member Woodward, who’s the resident expert on all facets of You Must Build a Boat. Listen to him when he tells you (through his book) about the different monsters, their strengths, and their weaknesses. The book will also tell you about dungeons or quests with specific modifiers, so do check it out if you’re in doubt about anything. It will tell you what those modifiers mean, and help you tweak your battle plan accordingly.
You’ll only end up wasting your attack tiles if you match them just as you’re moving between two enemies or two treasure chests. The only time you can attack enemies is if they’re adjacent to you, or if you’ve got a bow or a magic spell and are within the prescribed distance. When it comes to treasure chests, any key match you make in between them won’t count towards unlocking them.
When you see a trap on your display and match tiles from any distance, that will disarm the trap regardless of how far you are from it.
You’ll get a brief respite between enemies and treasure chests, and again when you make it to a new part of a dungeon, or when its Roman numeral indicator levels up. Take advantage of this quick break by matching power, shield, and thought tiles so you’ll have enough space for equipment and keys.
When you match crates, you’ll get yourself item tiles, and that’ll allow you to acquire new bows or bombs, new food items, and new spells as well. Bombs can be used to break all crates, food gives your character more energy, while bows and spells can be used as ranged weapons. Use that food immediately, and make sure you don’t overshoot and unlock too many items, as they can take up quite a lot of board space in YMBAB.