On legendary,permadeath
Study the connections of locations in relation to one another and take note the closing conditions. Some maps have deadend locations, and might be (quite often ) better to assign someone there even though none of your party is good at closing them (bust up the blessings)
Take advantage of scrying items or spell, even if its bottom scrying (Brodert). If you know a location has an henchmen early, it might be better to hold off on extra exploring it or busting blessing/allies. It might be better to just put a character there an explore normally, use its blessings for assist instead, so that when you encounter the Boss at other location you can just close it without combat. (Specially good on scenarios that buff up bosses for every henchmen kill)
Get the Holy Candle everytime. And use it rightaway. Same with Heal Potion and Cure. A turn you leave them on your hand is an extra explore or blessing not used and not drawn on
Recharge those Magic armors. Discard those extra weapons. Except on late rounds where you down a couple locations and the Boss have a damage first ability.
Know the number of Monsters including Henchmen/Bosses in a locations. Some characters ( depending on builds ) just isnt plain cut right to combat early on ( Lini/Lem )..put them on locations with 1-2 monsters so they can assist and spend their Aids/Blessings on other locations safely and if they do encounter and get beat up on their turn, they discard nothing or trash cards.
Put auto-success Items on characters that have low stats on such items. ( Amulet of Fortitude on Ezren ). Its given to put Characters on locations they are good on (Ezren on Academy, Merisiel on Guardhouse, etc. ) but after that, moving to the next location where they can close efficiently usually involves passing on locations they suck at. Here's why you put those item on them.
Take advantage of Ambush. If you've downed the location deck to 1 or 2 monsters..its better to fail on Ambush and get free explorations and be lucky to face a henchmen or boss via Ambush. Saves time..a lot ^^
Don't rush the game. When you start the game fresh with a new party, its ok to fail. Early on focus on getting chests and items/weapons. You don't want to move into higher tier and be under
Just my 2 zeni.