I´m going to tell you how I make the renders of my models.
1: Make a ground plane.
It shall be gray if the model is not textured.
If the model is textured,you can use grass,ground or whatever you think that looks fine.
2: Place a Skylight.
You can place it anywhere,it doesn´t matter.
3: Adjust the settings
Activate "Cast shadows" and then at "Rays per sample" box write "3"
4: Now render the perspective window and make sure the position of the camera and everything is correct.
Also,make sure that no background is seen,just the ground plane must be seen.
Click F10 and then click render.
5: If it is correct,change "Rays per Sample" to "20"
Now you have a good render