Reset transforms
Position, rotation and scale of the object should be reset before exporting the file. When the file is imported into any 3d software, its location and rotation values should be all 0 and scale should be at 100%.
In 3ds Max:
In Blender:
Centered origin
Geometry pivot should be centered on the mesh with the Z value being at the object’s lowest point with the object then being placed in the scene center. Bottom of the model should be sitting on the ground plane, it should not be floating or be positioned below it.
No extra objects
Model file should only contain the mesh object(s), there should not be any cameras, lights, dummies or any other extra objects. If the model is animated then some type of bones or armature can be included.
Realistic object scale
If the model is using a real object as a reference, its size should match the real object scale as much as possible. If no real reference was used, the scale should be set so the size looks realistic, for example the seat on a simple chair will generally be around 45cm high.