Use the colour wheel as the basis for a single colourfull illuration that could be tessellated across the wrapping paper? color theory chart - beautifully simply way to learn this (plus the fact that I suck at combining colors LOL!
Here you see warm and cold colours. Warm colours are made with red , yellow and orange, they make you think about the warmth and make it cozie. Cold colours are blue, green and light purple they make you think about water and cold.