I suggest starting by painting a nice coloured ground. This will govern the atmosphere for the rest of your image. I've used a soft pink to suggest a still, calm feeling and it also subtly suggests a desire for strawberry milk to the viewer.
Cats are well know for being bad still-standers and so you might find it helpful to fix your cats feet to the floor in some way. Baggy made quite a fuss when I did this so I quickly painted his legs first and then let him go.
