Loc: Washington State, King County
I think it depends on what you mean by "desert". I think that few camp in true desert. Folks often refer to the first 700 miles of the PCT as "the desert", but it's not --- it is dry, water is an issue, etc, but still.
As far as "relatively hot, dry" backpacking areas, there are lots of tips out there if you do even a hasty search. Here's one good example, one that I pretty much entirely agree with. Some others include this one, and this one. There are surely more.
I don't mean to cut off discussion with the above (!), but also see no sense in regurgitating old chestnuts that are already well defined --- i.e., more interesting IMO to discuss in the context of an existing base of knowledge. For example, I think there can be some debate over the merits of long-sleeved loose clothing vs. going in shorts and t-shirt (I favor the former). Or the right type of water containers, or use of inflatable mattresses or not, or concerns about snakes when night hiking, or use of an umbrella or not, etc etc.
Loc: San Diego CA
I could not come up with a top 10 list for anything to save my life. Even top 10 beers would be a struggle. I agree with Brian that this discussion would benefit from a little focus because the topic is a little broad. So.......
Best time to go backpacking in the desert? Fall, Winter, and Spring. Cooler temps, the snakes are not out as much (but if it is warm they will be out), and in Spring there are the flowers.
Loc: San Diego CA
Finallyme beat me too it. Not to get too touchy-feely about it but each area has its own feel and rhythm; you know, stuff like when the rains come. Because if there is anything important to know about desert backpacking, its understanding your water sources. Don't be expecting to extract water from prickly pear using a solar still after a prolonged dry period.
I personally really enjoy the deserts. They can be very raw and magical places.
Loc: California (southern)
You would be surprised by how many people drown in the desert - usually from flash floods. Depending upon your desert and location, there are also some really phenomenal trees, both large and small. It's just simply that there are not a lot of trees all crowded together.
I find this to be a fairly odd thread in that it is lumping together many,many different environments and ecosystems under one generic term. Consider "10 most important mountain camping facts." What would you make of a question like that?
I live and backpack in the Sonoran Desert. Some of my ten things here are different than my ten things I would pick backpacking in the mountains of Colorado again.
1. Lots of extra water. I hike where there might be no pooled water for miles and miles. Just did it a couple of days ago, in fact. Three of us went in with a minimum of 6 liters each... it was not enough. Heckuva story though... 2. Good topo map. I did not need this so much in Colorado because pooled water was not hard to find there. Here you need the topo in order to plan a relatively easy route to a possible water source. 3. Hat (mine is a very thin, white cotton ballcap) and a triangle bandage (military cravat from medic kit) for shade to the ears and neck. 4. A Lighter (on all of my lists) 5.Trekking poles (on all of my lists) 6. A quality, full tang, fixed blade knife. (on all of my lists) 7. A hiking partner (more important to me here than elsewhere, AND this does not make my pack any heavier!) 8. The ability to disinfect the nasty, horrible, fetid water I do need to drink out here. 9. Knowledge of the area I am heading into. Whether first-hand from a friend or via internet/books.