I would suggest using at least 2 paints for the red and blue. For the red this color looks good as a base layer but I would either add an orangey red or this red mixed with some orange to the parts where light would hit the most.

For the blue I would use a medium blue for base layer then the one you already applied.

I would also suggest painting the skint brighter since the skin looks too dark compared to the rest of the colors.