After thinking about u don't see(?) 2 Rules...
- High Quality
Like this, it looks like the Paper is dirty because of the Lightning on the pic.. Is it a Photo? Or a scan?
- As Big as Possible
Imagine this Pic on a Flag.. It's much too small or you will see as much pixel like hell...
Tipps for future:Draw your lineart with hand, scan it in pure Black/white and color it on pc

*hugs*