As you are preparing a room for a newborn and redecorating for a growing child, finding storage space I would say is essential. It is amazing how much can be accumulated to provide a child with clothes, toys, books, hobbies etc.
For the baby, you will need space to put away clothes, blankets, diapers, changing items, and gifts that they will use later. Your older child will accumulate more clothes, toys, books, things needed for hobbies and school. Getting space for storage to organize all these things will make the life of your children and your life as a parent much more pleasant and orderly!
I would consider the choice of colour for the room quite carefully. The room, I feel, should be conducive to rest. Your baby and toddler need to get enough sleep every day and night. Well-rested children learn and develop better than those who are always tired. So, while you want to make the room stimulating while they are awake, you also want to make sure that they sleep well. I would suggest that instead of painting each wall of the nursery with bright primary colours, think about a more mellow and restful pastel backdrop with bright, primary colours as either a border or pieces of furniture. Why not go for a jungle theme? Choose a colourful, bright jungle border, or a jungle carpet. Soft toy snakes and colourful stuffed birds or butterfly cutouts can add to the decor. Make pillows of animal or jungle prints and use themed accessories.