I am new to all so bare with me.
I have assets in fbx, with the materials etc. I tried importing one and it was like 1/100th of the scale that it should have been. I couldn’t for the life of me find a scale button inside of UE4.
Also how do you guys keep thousands of materials/assets organized? Would like to see a tutorial on that. If every asset has a bunch of materials, and you have 1000 assets it would get very confusing I am guessing.
Man how did you even get your fbx to import…?
The size system in UE4 is 1cm = 1 uu (uu = Unreal Unit), so when you are exporting out of your 3d program, make sure the Units size is set to centimeters. In 3dsMax, click Customize -> Units setup, and make sure the system units are set to cm.
For the scale tool, the easiest way to bring it up, is to select the item in the viewport, and then press the “R” key. only works if no other key is pressed (for example holding the right mouse button and presssing W would move the camera forward).
The editor shortcuts are: W = Move - E = Rotate - R = scale
The asset is really up to your preferences, I prefer to keep all my materials in Game\Materials folder, textures in in Game\Textures, etc. Also, so you can easily tell the difference between them, all materials I make are named “M_xxx”, textures “T_xxx”, blueprints “BP_xxx” (where xxx = the name of the asset) etc. But use whichever method is easiest for you! 
You also have to export the mesh with cm!! -> e.g in 3ds you can choose that in the export window
A good folder structure and names are really important to keep the overview because especially when you create a big game you will have tons of assets -> also use parent materials. With that it get’s easier to keep the overview over the materials.