So, I can't embed images into an src guide so each of the floors have been broken up into imgur links. I briefly go around how to spot and navigate the various ways in which floors can spawn:

1. Keep of the Lead Lord https://imgur.com/a/f0d87

2. Gungeon Proper https://imgur.com/a/Fzb1C

3. Black Powder Mine https://imgur.com/a/IjdXc

4. Hollow https://imgur.com/a/6nKlO

5. Forge https://imgur.com/a/BGLZk

In order to spot things like loops and such, just think about how the maps physically fit together. The most obvious example is the Dragun room, which is really tall. It will very rarely spawn 'beneath' a bunch of rooms on the map.