Someone to talk to about watering. Different plants have different evapotranspiration rates and will have been planted in differing soils (re drainage) and may be living in differing micro environments and have shallow or deep roots at this time. If someone is pretty smart there, they'll have an idea how to answer re your plants in your particular area. Going in with a list of your plants could be helpful.
Some of the garden centers of my past were started by people who know a lot, so sometimes the higher up people are good to talk with; on the other hand, in a good shop, sometimes the employees are pretty swift.
A lot of natives when first planted will need some water for the first year or two until they are well established, and then can be let go on their own. But, since you're in the Mohave, I'd ask locals about that.
Me, I look at the leaves.