Yorick lane starts with grave count: if you do not have graves banked, you usually do not have a trade, so look to tag E on a last-hit or after their dash and place W on the route they need rather than opening with a blind cage
Maiden is a map piece, not just combat stats—keep her attached when you need the full duel, and only release her with enough time and lane length that she is already forcing a side-wave answer before the objective setup starts
Yorick's best games keep making the same answer come back to a worse lane, and the data says his leads lose a lot of bite when they turn into long games without real structure damage behind them
Release Maiden when the side wave will start asking a question before the next important map moment, not when you simply have ult available. If dragon, Baron, or a forced mid setup is coming soon, send her early enough that the wave is already crossing river and someone has to choose between answering her or matching you. Keep her attached when you expect a real duel, need full threat to break the top matchup, or cannot trust the lane to protect her. A good shortcut is this: if releasing her will only get one wave and die alone, keep her; if it will pull a defender on a timing that changes the map, send her.
The Cursed Horde: Yorick can summon Mist Walkers to swarm and attack nearby enemies.
Yorick deals bonus damage on his next attack and heals himself. If the target is a champion or large monster or if the target dies, a grave will be dug.
Yorick summons a destructible wall at target location that will block enemy movement.
Yorick throws a globule of Black Mist that reduces armor, damages, slows and marks enemies. Summoned units gain move speed when moving towards marked targets.
Yorick summons the Maiden of the Mist that causes Yorick's attacks against the Maiden's target to deal bonus damage. The Maiden will also automatically raise Walkers from dead enemies.