Starting with titanium white mixed with matte glaze (to match the wall finish) I blocked in the clouds with a natural sponge, dabbing in the shapes and building up opacity. Later, after stepping back, I decided that the clouds weren't showing up enough against the beige wall so I thinned out a mix of my yellow accent color with glaze and worked it over the shadow areas with my sponge. This is a great technique to use for super-thin layers and very soft blending- great for kid's mural. After glazing some thin white over to set those shadows back a bit into the clouds, I painting in the planes with brushes and kept very simplified so they would resemble a print and not detract from the clouds.
This mural was a great lesson is working with what you have already, blending with glaze and a sponge, and time management. It took me about three sessions of three hours each to complete. Keeping the sessions short made sure that I kept working evenly instead of getting obsessive over small areas. Every time I came in the room for a new session I saw it with fresh eyes and was able to better pinpoint the areas that needed work. Towards the end of each period I started to experiance some muscle aches, especially when I was working on areas higher than my shoulder- so give yourself plenty of time to recover in between.
Alright, hope that was informative, I sure learned a lot!