The Sunset garden books are ideal for your situation and have many wonderful versions full of great ideas in pictures.

There was a recent thread from someone with a similar situation, and I think it was also in southern CA. You might want to search the forums first for plantings on slopes, also post in your regional forum. Books from the library that focus on gardening in your region may give you some ideas of possible "looks" and what plants to use to achieve them. Once you have a list of plants that will do well in your area, you can research them further. Finding pictures to post might be more time consuming than can be expected from forum members. You might also want to lurk on the New to Gardening, Perennial, and Shrub forums to learn some basics. Are you going to design this planting yourself? If so, you'll need to do a lot of research and planning to come up with a presentable design. Expect to spend six months to a year studying the plants that you might use, looking at other designers' work for ideas, learning some basics. If you don't care if it looks fabulous and just want some plants to hold the slope, the forums mention above will provide some plant suggestions, and you can charge ahead. If you need help, designers charge anywhere from about $80 to $125 per hour, probably at the high end or more in your area. It can take a couple of hours just to talk figure out what you want and measure the area in question, and design time would be on top of that, how much depends on the complexity of the design. Search for threads on working with a designer to get a feel for what to expect. If you plan on hiring out the actual preparation and planting, landscape contractors can give you a quote based on a detailed drawing and plant list. Some landscape installers also design, but be sure to ask to see a portfolio of installed jobs to see if you like their work. Not all are trained or experienced enough in design to do more than a ho-hum planting. Some are very good. It's impossible to guess what it might cost, even if you gave the dimensions of the area to be planted, because the type of plants selected, quality of other materials used, and density and complexity of the planting will all affect the cost. An experienced landscape designer or architect can work within a budget you set for them, or tell you if you are being realistic in the amount you want to spend. Any project can be scaled back with more common plants, smaller size at planting, etc. Expect to pay a designer for their time on a consultation, usually one hour, which is spent (by both parties) finding out if your project and their skills are a good fit, whether you can afford a full design or whether an hourly consultation is possible instead, and whether you are on the same page, aesthetically.

Thanks for your appreciation for my approach, s8us89ds, and I like the the points you have made about opportunities to create habitat and ecosystems. (Disclosure: I am a restoration ecologist, by profession, and this is what I do, even at home: create habitat.) I've observed that birds, in particular, find my yard more a more useful and better place to hang out than elsewhere in the neighborhood, which is a 1970s tract development with lots generally in the 1/5- to 1/3- acre range. This is a big plus, aesthetically, for me, along with the visual pleasure of the tapestry of chaparral plants. The other great advantage to taking this approach, as you point out, is that it is inexpensive and can pretty much be done by anyone who can dig a minimal planting hole in unimproved soil (what you want when planting natives) while standing on a steep slope. Blanchette, a bit of advice, with reference to "craning in" large oaks or olives. Planting a relatively modest-sized tree and letting it establish from a younger age invariably works out better, in my experience, than the instant (but generally short-lived) gratification of installing a large tree. Beyond the eye-popping expense of buying and installing mega-trees, there are often major, years-long problems with establishment that need to be skillfully managed when using such trees. Fine if you are up to doing that, but often a disappointment. Case in point: about 10 years ago, a neighbor a few houses up my street had a very large olive tree (was at least the 300-gallon size) installed (using a crane, etc.) in his front yard about the same time I planted a gallon-sized olive in my back yard. His tree has developed significant root problems and it has lost two-thirds of its canopy; the tree is, at best, barely surviving and unhealthy -- not to mention disfigured because of major branches having to be amputated. The olive tree I planted is now larger than his (in fact, is currently about the same size he started with) and quite healthy. I personally won't plant anything larger than a gallon-sized plant and consider 5-gallon the upper limit.

This problem would be best explored in plan view. Prepare a base plan showing the existing hardscape features, property limits and tree trunk locations. How you run the fence would depend on those things in addition to the shape, size and location of the pool. Your thread title indicates that grade is major constraint, but it does not show in the photos you've provided. You'll need to find a way to make it obvious in the pictures.