Adobe is one of the oldest materials used for construction known to man. Basically adobe is just dirt that has been moistened with water, sometimes chopped straw or other fibrous material is added for strength and then allowed to dry in the desired shape.
It was found that by shaping the material into bricks shaped blocks a more uniformed shape could be formed, but the adobe can be simply piled up over time to make a structure.
The trick for mixing adobe is not to use too much clay, the recommended amount is between 15 and 30%. If too much clay is used the building could crack as the clay shrinks but use too little and the material could fragment.
A more modern way of making adobe is to add a small amount of cement or asphalt emulsion to help stabilise the mixture and keep it intact where the weather is bad.
Adobe buildings have large eaves (over hanging edged of roof) this helps to steer the water away from the walls and foundation.
Some houses are plastered with cement on the outside in an attempt to protect the adobe, but it has caused problems when moisture finds its way in through the cracks in the cement and there is no where for it to evaporate.
Although adobe is a good thermal mass material it is not a good insulator, this means that another means of proven insulation is required, this can be done by creating a double wall, with an air space (a bit like double glazing) or by putting some sort of insulating material on the outside.