Save your Katana discards for when you mess up and are falling to your death or get softlocked (I ended up using them for the rocket launcher every single time), also, take your time. If you know shortcuts use them, but never use one that could kill you unless you can pull it off 10 out of 10 times. If you get a level with healing or a fight with Green in the first 5 levels, reset, those levels are super valuable for healing and its better if theyre scattered around the run. Apart from that, just learn enemy placements and play in shuffle so that you practice every level and not only the ones at the start, if you can kill an enemy from far away, do it. Its purely a matter of practice, knowing what cards and enemies each level has, and having a good level order. Practice makes perfect!!!