Painting around the toilet can be very difficult, without getting it all over the toilet. When we painted our bathroom, we used saran wrap to protect the toilet. This worked really well. Simply remove the tank top and wrap with saran wrap.
Since then, I found a tutorial from Houseof Hepworths, where she used a garbage bag, instead.
Either way will help protect your toilet from getting paint all over it. Makes it so much easier!