Defining your xeric garden style will depend greatly on your own personal style, and on the style of your house or other buildings on your property. Slavishly copying someone else's xeric garden style is not necessarily right for you, but by all means adapt ideas from garden styles of other countries, xeric or otherwise.
Various areas of your garden can have different styles as long as there is enough space between them, or some feature that will give some consistency to your style.
This will give the design of your xeric garden consistency.
Find the xeric garden projects that will define your style.
The crucial aspect of the cohesiveness is not necessarily the rocks themselves, as they are all different, but the use of groundcovers and mosses to tie the look together and soften and blur the outlines.
Form a foundation around that central idea and leave out the parts that don't appeal to you.
A mish mash of styles will not make an appealing garden; there still needs to be coherence and cohesion.
Too many differing styles will create a sense of unease, so keep to one or two types of textures in your paving, retaining walls and other hardscaping. Using wood chips and wood blocks and boardwalks will combine to form a rustic feel. Granite chips combined with concrete pavers, or red clay bricks with lava rock mulch all blend together in a harmonious grouping.
Mulching with a material that complements all the other features is the finishing touch.
Making a dry stream bed is a fun way of introducing the concept of running water into your garden, without any water at all.
You'll never hear the gush and gurgle of a mountain stream, but your imagination can easily fill it in the blanks.
The illusion of the burbling brook is real, even before any planting is done.
Pinning down your xeric garden style can be as simple as recognizing the universal attraction to water and adding a unique and interesting water feature to your plan.
Using salvaged construction materials, such as this well ring, you can make a perfect small water feature to add some white noise to a front garden.
A circulating pump runs the little waterfall, which attracts birds to drink, and also oxygenates the water for the plants that live in it.
A handful of little miniature cattails, some duckweed, and you have a microcosm in a small space.
Something as simple as an old well casing with a liner can make a great water feature...even if you're conserving water
And, of course, every xeric garden should include at least one pond, preferably one that is attractive to wildlife and birds. Depending on the size of your yard, make the pond as big as possible to create an environment that will attract many small creatures to drink, hunt and raise their families.
I've had a lot of enjoyment out of watching the nestlings of my migratory visitors learn how to have a bath, seeing the dragonflies hatch out on the reeds, and watching the progress of the tiny salamanders as they grow from aquatic tadpoles to fully amphibious lizards.
Whatever path the inspiration takes, using your instincts can help you to pin down the xeric garden style that most appeals to you. Using a technique I like to call 'cogitating' or visualizing is most useful.
Cogitating consists of staying still in a comfortable place and letting the landscape speak to you. It's not mysterious, it's just your inner animal having its say. Listen to it, as it's quite often right.