Despite living where I do, and having grown up in the temperate rainforest, I've always had a fascination with the desert and spent a year traveling and observing desert bio-geography in the SW USA, as well as watching tons of videos on it, and reading online and in
books.
A few things to consider:
-I would definitely swale your hill.
...the hill is your defining feature, but I would at this time get you to try to
envision it as a pond.
It is obviously not a pond,
but it could become a massive reserve of in-the-ground water for your property.
...a shallow catchment on the top of the hill begins the charging of the deep central area of the hill, and slowly builds a water table within it. If you have access to any woody debris from anywhere, the base of this pond might be a good place to bury it. The depth of the mound will resist evaporation, and the capillary action up through the aggregates due to evaporation will permeate the mass of the mound with moisture during heating, even though you will probably not be able to tell right away, even after it rains... it's relative to what it is now. Dig the pond slightly deeper on the south side. All material dug out of the pond should probably be placed so that it encourages shade on the deeper part of your 'pond' thus gaining the most water before evaporation can take place. Any swales on the slopes will continue infiltrating water into the depth of the hill, which will accumulate, and eventually make your hill a water source.
...depending on the slope, which obviously varies somewhat, and as others have mentioned, build your swales in accordance with any natural features/obstructions on the hill, with the idea that you will be wanting your mulberries and figs and whatnot to have room to grow and you will have space to work around them.
...-build a swale around the base of your hill, maybe ten feet away, and plant some of your dates along that edge. This will give you
deep roots where you need to keep your water resource and function it as part of your landcape around the hill.
...when you build your swale around the base of the hill, you will notice where the lowest area is, as the swale will be slightly further from the hill. This will be the Oasis of your Gher. Geoff Lawton did a video about a gher, which is more of a large dune but serves the same bio-geographic purpose, that if you can find (I'll try to find it later), will be a great resource. The base of your hill will weep water to this one spot the most, and this would be the best place to concentrate a future oasis/orchard with Date Palms as your over-story
canopy.
...wander your property and look for any spots that show where water has eroded the landcape in large rain events. Concentrate the rest of your landscaping and plantings in these areas. ditch/swale/pond these water channels out of these areas into the landscape. Anything that you can to impede the flow of water by slowing it, being it the placement of individual rocks or making gambions, will keep the water in your property as long as possible so that it infiltrates.
-A wheelbarrow path is your friend! Build one up the ridge of your hill to the top, with side branches that go into your swales for easy access.
-Plantings:
...the pods of mesquite are extremely nutritious, and as mentioned are a fantastic nitrogen fixer/nurse tree/microclimate, so get these established everywhere that you are planning to get food systems in place. There are other nitrogen fixers that are native to the SW which could also be useful for the same reasons as mesquite. Research them, get them, plant them. Once they are established then you have multiple wells and pumps bringing water from the sub soil depths to your surface and air. After a time, you have the benefit of chop and drop, and or the techniques of coppicing and those used in
Farmer Managed Natural Regeneration
...get prickly pear (some varieties have edible thornless pads (nopalito), and some are better for fruit-delicious!) and other edible cacti, once you have the water available to get them through the initial rooting phase. These make great fences and/or biomass for other things.
...ocatillo is an amazing plant used for fences in the SW Indigenous villages, along with prickly pear. After a large rain event, the plant, normally just a long thorny bunch of stalks, produces sprouts of leaves to maximize
solar gain (instead of just using it's thorns for photosynthesis). These leaves happen to be absolutely delicious.
...you will have to dampen/shade, and otherwise nurse all your plantings until the rains/roots have found critical mass.
...all plantings should include buried wood/biomass and be in catchments that can be mulched.