It depends on what desert environment we're talking about, but broadly speaking I'd focus on finding food plots first, and hunt from there. Look within a mile or two of the food for north-facing shade (can go further in some places), especially at the bases of rock-outcroppings/rimrock, and glass the daylights out of those bedding areas. Even moreso if you can find ones that are higher up a slope, as it helps them with both visual security and catching thermals. Don't worry about where they water.
If you hunt an area that has any ag fields around, you can drive the perimeter of a lot of those places on dirt roads, and try to cut sign as you drive or walk, depending on how good your eyes are. Their tracks can often stand out pretty starkly crossing dirt roads and two-tracks. Sometimes you'll even find established trails through the brush, between where they bed and where they prefer to enter the fields. Those can be great places to get pointed to their bedding areas, and to find an ambush spot.