quick photoshop question

I made this sketch of Rodney which I colored with markers, only to be reminded why I stopped working with them. Is there any way to get rid of the grainy texture? I like to see a bit of paper structure or texture in my artwork, but this is way too pronounced (it's even more pronounced in a higher resolution). ( sketch behind the cut )

Also, to celebrate my mini-vacation, I want to do fanart. I got a couple ideas, but I'm taking prompts too. Anybody? (it just gotta be SGA, and gen)