Play other stuff before going into K3, most people (I'm including myself in this) play the game when it's still way too far from their skill level.
Now the only tip I could give is pointless since you haven't reached the item room, but if anyone is interested:
Exploit the Warpsaves glitch. Which is basically pressing S+your shoot button at the same time, while touching a save that allows you to warp when pressing S. This makes you save on the spot where you would be after "escaping", but still on the room where the save you warped from is. If you do this on Item 1 room, you will save on a spike to the left of the item, but you won't die to it if you hold right as you spawn.
It's a very weird glitch, I'm pretty sure it has to do with the order events are executed in GM.
PS: The glitch is only useful in Item 1 and maaaybe item 3 (haven't tested yet, but seems like you could skip a couple segments). So it's pretty much useless since it only allows partially skipping the easy secrets.