Here is the usual arrangement of my palette. I start in the upper left and work light to dark and warm to cool with my earth colors separated at the bottom. Put out more paint than you think you will use. This will free you to paint thickly without worrying about having enough paint on the palette.
In this picture I am preparing to start my underpainting using Yellow Ochre and Burnt Sienna so I have only placed a small amount of the other colors as place holders so you can see my arrangement.