How to render footage out of Premier Pro without it being grainy?

I'm shooting on a Nikon D3100 DSLR. When I render my footage out at 1080p, it comes out really grainy. I want the footage to be as smooth as possible. Is it the camera settings I'm using or am I doing something wrong?

What you are calling "grainy" is actually noise.

Noise is a function not having enough light to illuminate the scene and the camera automatically raising the ISO to accommodate you shooting the video

How much education do you have in the field of shooting video, righting scripts, setting lighting and editing video?

It is NOT all about having all the right gear, but knowing how to use what you have. Using the "try and fail" method to produce video is for sure frustrating, but also it is difficult to have any confidence that at any given time, you can produce high quality video on demand

By the time you have your raw footage to the editing phase, it is far too late to fix anything as damaging as not having enough light on the set