
Super Secret rooms almost always spawn near the boss room.You can move cards and trinkets into different rooms now which may be useful for playing more optimally.Save your D6 charges for the devil room primarily.Explosive enemies like mullibooms and those green ipecac guys can be used to check for secret rooms/to destroy objects.Always blow up as many rocks as possible in case of finding a black market.Tinted rocks always have a way of telling what they are, and they can drop small rock and lucky rock.Bombing those round red rocks in the womb can drop blood clot or placenta or harlequin baby.Bombing skulls in the depths/necropolis can drop cards, runes, black hearts, ghost baby and dry baby.
Bombing mushrooms in the caves drops mushroom items (liberty cap, magic mush, mini mush). Bombing pots in the basement/cellar can give the swallowed penny/quarter. Don't use resources early in a floor, you may need them for something else later. Check all sides of rooms before wasting bombs as secret rooms always are accessible from all adjacent rooms directly, meaning there won't be any rocks/enemies at the entrance to the secret room. If you get to the devil room without going through the boss (joker card/red chest) you should try to take red heart damage on the boss to make sure you don't get the door, this way the game won't count you as having got a devil deal on this floor, making it more likely on later floors. Don't take red heart damage so you have a chance of getting the devil deal room. Without this you can't get an arcade (which only spawn on even numbered floors.
Save 5 coins when leaving odd numberered floors (most important on floor 1).