Consider using the methods in the section Management of Urban Ecosystems. Are there ways that you might trap storm water to increase water infiltration, use gray water for reuse in irrigation, or even grow food for yourself and for urban adapted wildlife, such as some birds, butterflies and lizards?
Whenever possible, preserve valuable existing vegetation, such as mature trees for shade and bird nesting sites.
Tree species selection is important. Plant "the right tree in the right place" to meet your space requirements, use objectives, and to minimize maintenance, water, and expense. Shade windows and south facing walls with deciduous trees. Deciduous trees lose their leaves in winter, allowing solar rays to reach and warm the house.
Note: When using local native plants in landscaping, consider that most natives grow during our rainy season, fall through spring. With the exception of water-thirsty riparian types, most southern California native plants are dormant or slow-growing in the summer. This is the opposite for common landscape plants that grow slowly, or not at all during the winter, but require regular irrigation throughout the summer.