Okay so, when I started out mapping their we're a few things that I really wish someone had thrown into a quick tutorial on how to make life easier. So what I'm doing is throwing some of those in this that i have learned, they are literally the simplest things so if your not a beginner you may be wasting your time.
Have you ever selected a long wall and just wished that when you duplicated it and rotated it to make an adjacent wall it would rotate how everything else normally does around a central anchor point, well heres how to do that.
Simply select the items you want to rotate/flip/spin and press B. you will notice your selection zone has turned red and when you rotate it, it moves around a central pivot point. This is a compound, and it will cut your mapping time down a few hours.
Surfaced Object Placement:
When you first go to place an object/entity you will notice it only shows a low detail wireframe around the shape of the object. This can cause frustrations by not being able to see the full detail of the objects placement, and may cause you to have to deal with cracks between your primitives, walls, whatever.
Simply hold down the the right click button while placing an object to see a fully surfaced version of what your placing.
To enter a full detailed wireframe mode while using the perspective viewport simply go into View-Render Mode and check off the wireframe bar. This will assist with seeing a small room through a two story building without zooming all the way in and adding items in drawers and cabinets with ease.
Thats it, comment below if you have a tutorial that you would like to see, but haven't found anywhere.