I had great fun with my first pet portrait attempt

I had great fun with my first pet portrait attempt - student project

I've saved this course about a week ago, but had no time to go through on it. Today however my fiancé asked me whether I can do some portraits about our dog, just so we can put it out on our wall. So I had no more time to waste and get on the course asap. 

It has given me a good boost and I've got some really nice pics. 

But, I still struggle with the same issue as always. I used my Nikon D3300 body with kit lens and with 50mm lens as well, but none of my pics turned out sharp enough. They all have a lot of grain, even on a low ISO setting. I'm not sure why it's happening and that issue put me off of photography for quite a long time. Any suggestion? 

Thank you in advance. I had great fun with my first pet portrait attempt - image 1 - student projectI had great fun with my first pet portrait attempt - image 2 - student projectI had great fun with my first pet portrait attempt - image 3 - student projectI had great fun with my first pet portrait attempt - image 4 - student project