Aside from the navigation aspect, here are some basics to help for runs.

Dashes are used to move around quickly, especially useful in later scenes having much bigger rooms and avoiding projectiles with invincibility frames. Hence the first upgrades going for extra dashes (5 ideally for scene 1) and jewel recovery time on 4th and 5th line.

It is very important for Scene 3 since the start will always be 3 HP and 3 jewel charges for each Scene, so getting past floor 1 quickly is often crucial there.

One would want at least 6-7 jewels overall for Scene 2 and 7-8 for 3. Dash attacks are often avoided because the recovery is much longer and often gets Remilia hit. Each hit will cost at least 1 or 2 second depending on the positioning.

There is also a dash and dash attack upgrade that make them go quicker and have less recovery time.

Upgrades on floor 2 is used for downward shuriken and upward spear upgrade (penultimate lines) to make them last longer and deal more damage and can be used for protection to cancel small rounded bullets. A more efficient upgrade would be to go for raw damage on 1st line but is more dangerous. Then it's mostly focusing on upgrading the 2 abilities and stats to gain efficiency on the end scene bosses with the jewel count.

Meiling is useful to avoid spending points on health (last line), if possible maintaining at most 5HP before entering a new floor. Getting back to 2-3HP costs 50 per HP and 100 back to 4-5HP. Going higher will cost at least 500 each.

Ideally a run would want the gatekeeper to spawn in the starting room and be a fairy since they don't move a lot. Unlike kedama bosses they can take damage at any time and have safe spots to damage them freely.

Entering doors back and forth will change the layout of the spawns, useful to try to get a boss near the green exit door. There is a small possibility that a boss spawns inside a wall or floor, so entering a door is also useful to avoid softlocks.

Because Scene 3 can have higher enemy density rooms, special gauge can be used midway through the scene to get invincibility or to clear the gatekeeper quickly without taking big damage and still have it full for the boss.

Scene 1 boss: Rumia can be dealt in one Special Charge cycle, but depending on the efficiency from the earlier floors, the gauge might not be fully charged upon entering Floor 10.

Scene 2 Boss: Cirno can also be one cycled in one special charge if she stays on the ceiling with the dash attacks, requires luck otherwise it will be a lengthy fight usually.

Scene 3 Boss: Marisa will avoid Remilia during most attacks, thus starting to the right to get her near Reimu is ideal. Both have hitboxes and on good condition can be one cycled sith the special while dealing double damage (Boss health shared).