Beekissed
Garden Master
mulch will definitely help hold that moisture in. also if your location is exposed some windbreaks (not shading the plants but barriers a bit aways) will also help cut down on evaporative losses.
collecting rainwater is a great supplement to watering/rains.
if your soil is primarily sand find some clay. a few % will help sandy soil hold moisture and also nutrients. if you keep adding the organic materials it will be prime garden soil. go light with the clay. too much gets messy, but i'd really not want too sandy of soil in comparison.
Hard pan clay here...not a grain of sand in sight. That's one reason I'm using heavy mulch to build a topsoil layer and doing no till...if you till this stuff, it doesn't matter how much organic matter you put on it, it will consume it like it never was and leave the clay right on top, to grow hard as cement once again. If you till it, you have to KEEP tilling it and hilling it.