Things You Must do For All 3D Models

Set unit scale to .01 Meters (for proper unreal importing)

All models must have -Y as its forward axis

Name all objects (RTP_ObjectName)

Name all materials (RTP_ObjectName_MaterialName)

Pack the .blend file with any textures used, if textures where used

Apply all transforms

The origin point is at the base of the model and at the world origin

It is important that models are game ready. This means the topology should be made up of only triangles and quads. There should also be a reasonable balance between geometry and the level of detail.