The machine includes one #201 endmill.
The community has suggestions at: https://www.shapeoko.com/wiki/index.php/Endmills#Shapeoko_3
The nice thing about V carving is that it’s somewhat size independent — see: Carve letters depth
Best thing to do is to work through the tutorials at: http://docs.carbide3d.com/tutorials/#shapeoko-tutorials
and then branch out into projects which incrementally try out new concepts and aspects of the machine and software.