I have a big tip for anyone interested in completing this game... RAINBOW MODE. Seriously. Just finish a Blessing Run as soon as you possibly can. This will unlock the best weapon in the game "Gunther".
Then, always playon Rainbow Mode. On floor 1, just keep restarting until Gunther shows up. Then play as normal. Gunther is an infinite ammo weapon that increases in power after each room you complete. As it upgrades, it increases in damage, as well as automatically gets the Bouncy Bullets and Homing Bullets perks.Chances are, it will be at max power before you even finish the first boss. Then on each subsequent floor, pick a passive item that enhances your damage output, like Fat Bullets or Riddle of Lead.
If you want to make it even easier, play as the Robot and destroy every chest. The Robot gets a 5% damage boost for each piece of junk he is holding. If you get lucky, you'll find Sir Junkan somewhere along the way.
