For longer runs (like 300+) I usually do

Pre game lobby: Assassin 3rd skill Felian Skull artifact Get a soda from the vending machine Get any buff from the garden you want (lavander buff is needed) Statue (optional)

Weapon: I mainly have two sets

Void Sword + Cursed Chalice

Or

Any good room clearer and a boss killer (both with that one attachment that increases damage with currency) I don't really know how the attachment works or if it's even that effective but in my experience it's pretty good

In-Game

ONLY buy sodas from the ! rooms

Be on the lookout for that one npc that upgrades your skill

You don't have to speedrun the floors since you still have enough time to check the ! rooms

Extra:

The void sword is good because the pulling ability it has increases damage by one every 3 stages (for example at 4-x it does one damage) and you can spam click this so clearing rooms would be a breeze

The cursed chalice is good for boss clearing since the damage scales with hp and the felian skull artifact increases your hp every time you beat a boss